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Latent tuberculosis, caused by dormant Mycobacterium tuberculosis (Mtb), poses a threat to global health through the incubation of undiagnosed infections within the community. Dormant Mtb, which is phenotypically tolerant to antibiotics, accumulates triacylglycerol (TAG) utilizing fatty acids obtained from macrophage lipid droplets. TAG is vital to mycobacteria, serving as a cell envelope component and energy reservoir during latency. TAG synthesis occurs by sequential acylation of glycerol‐3‐phosphate, wherein the second acylation step is catalyzed by acylglycerol‐3‐phosphate acyltransferase (AGPAT), resulting in the production of phosphatidic acid (PA), a precursor for the synthesis of TAG and various phospholipids. Here, we have characterized a putative acyltransferase of Mtb encoded by Rv3816c. We found that Rv3816c has all four characteristic motifs of AGPAT, exists as a membrane‐bound enzyme, and functions as 1‐acylglycerol‐3‐phosphate acyltransferase. The enzyme could transfer the acyl group to acylglycerol‐3‐phosphate (LPA) from monounsaturated fatty acyl‐coenzyme A of chain length 16 or 18 to produce PA. Complementation of Escherichia coli PlsC mutant in vivo by Rv3816c confirmed that it functions as AGPAT. Its active site mutants, H43A and D48A, were incapable of transferring the acyl group to LPA in vitro and were not able to rescue the growth defect of E. coli PlsC mutant in vivo. Identifying Rv3816c as AGPAT and comparing its properties with other AGPAT homologs is not only a step toward understanding the TAG biosynthesis in mycobacteria but has the potential to explore it as a drug target. [ABSTRACT FROM AUTHOR]

Mulberry leaf is a widely used protein feed and is often used as a strategy to reduce feed costs and improve meat quality in the livestock industry. However, to date, there is a lack of research on the improvement of meat quality using mulberry leaves, and the exact mechanisms are not yet known. The results showed that fermented mulberry leaves significantly reduced backfat content but had no significant effect on intramuscular fat (IMF). Lipidomic analysis showed that 98 and 303 differential lipid molecules (p < 0.05) were identified in adipose and muscle tissues, respectively, including triglycerides (TG), phosphatidylcholine, phosphatidylethanolamine, sphingolipids, and especially TG; therefore, we analysed the acyl carbon atom number of TG. The statistical results of acyl with different carbon atom numbers of TG in adipose tissue showed that the acyl group containing 13 carbon atoms (C13) in TG was significantly upregulated, whereas C15, C16, C17, and C23 were significantly downregulated, whereas in muscle tissue, the C12, C19, C23, C25, and C26 in TG were significantly downregulated. Acyl changes in TG were different for different numbers of carbon atoms in different tissues. We found that the correlations of C (14–18) in adipose tissue were higher, but in muscle tissue, the correlations of C (18–26) were higher. Through pathway enrichment analysis, we identified six and four metabolic pathways with the highest contributions of differential lipid metabolites in adipose and muscle tissues respectively. These findings suggest that fermented mulberry leaves improve meat quality mainly by inhibiting TG deposition by downregulating medium‐ and short‐chain fatty acids in backfat tissue and long‐chain fatty acids in muscle tissue. [ABSTRACT FROM AUTHOR]

The 2H‐tetrahydro‐4,6‐dioxo‐1,2‐oxazine (TDO) ring, a rare structural motif embedded in the molecular architecture of alchivemycins, is synthesized from 2,2,6‐trimethyl‐4H‐1,3‐dioxin‐4‐one via two routes. Both routes involve the intramolecular trapping of an acylketene intermediate by an internal hydroxy group to form the TDO ring as a key step. The first synthesis was achieved in 29 % overall yield from the starting material by a four‐step sequence featuring a DMAP−CaCl2‐mediated O‐ to C‐acyl migration reaction to install an acyl group at the C5 position of the TDO ring. The second synthesis was completed in 8 % overall yield from the same starting material as the first one through five steps by exploiting a photo‐induced double bromination reaction. [ABSTRACT FROM AUTHOR]

Since the discovery of the sirtuin family founding member (i.e., the yeast silent information regulator 2 (sir2) protein) in 2000, more and more sirtuin proteins have been identified and are currently known to be present in organisms from all the three kingdoms of life (i.e., bacteria, archaea, and eukarya). Seven sirtuin proteins have been identified in mammals including humans, that is, SIRT1/2/3/4/5/6/7. Sirtuin proteins are a class of enzymes with primary catalytic activity being the β‐nicotinamide adenine dinucleotide (β‐NAD+ or NAD+)‐dependent deacylation from the Nε‐acyl‐lysine residues on cellular proteins. Many sirtuins (e.g., human SIRT1/2/3/4/5/6/7) have been found to each possess multiple individual deacylase activities acting on Nε‐acyl‐lysine substrates with different acyl groups ranging from the simple formyl and acetyl to the more complex groups like succinyl and myristoyl; however, our current knowledge on the (patho)physiological roles of these individual deacylase activities is still limited, which could be due to the currently still thin research toolbox for investigation (i.e., the deacylase‐selective sirtuin mutant and inhibitor/activator). In this article, an updated account on the subject matter will be presented with biochemical and medicinal chemistry perspectives. [ABSTRACT FROM AUTHOR]

We developed intramolecular carboxyamidations of alkyne‐tethered O‐acylhydroxamates followed by either thermally induced spontaneous or 4‐(dimethylamino)pyridine‐catalyzed O→O or O→N acyl group migration. Under iron‐catalyzed conditions, the carboxyamidation products were generated in high yield from both Z‐alkene and arene‐tethered substrates. DFT calculations indicate that the iron‐catalyzed carboxyamidation proceeds via a stepwise mechanism involving iron‐imidyl radical cyclization followed by intramolecular acyloxy transfer from the iron center to the alkenyl radical center to furnish the cis‐carboxyamidation product. Upon treatment with 4‐(dimethylamino)pyridine, the Z‐alkene‐tethered carboxyamidation products underwent selective O→O acyl migration to generate 2‐acyloxy‐5‐acyl pyrroles. Thermal O→N acyl migration occurs during carboxyamidation if the Z‐alkene linker contains an alkyl or an aryl substituent at the β‐position of the carbonyl group. On the other hand, the arene linker‐containing compounds selectively undergo O→N acyl migration to generate N‐acyl‐3‐acylisoindolinones, and the corresponding O→O acyl migration forming isoindole derivatives was not observed. [ABSTRACT FROM AUTHOR]

A selective reaction of bridged ozonides with Fe(II) salts proceeds through the sequence of O−O, C−C scissions and halogenation to form α‐halogen substituted δ‐ketoesters and δ‐diketones in 15–72% yields. The overall sequence shows how a temporary installation of a peroxide functionality can be used to replace the acyl group within an acetoacetic ester unit with a halogen. [ABSTRACT FROM AUTHOR]

Chemical modification of starch from the chayote root (Sechium edule Jacq) is carried out with lauric acid and acetic anhydride. The modified starch is characterized by Fourier‐transform infrared spectrometry (FTIR), X‐ray diffraction (XRD), and Differential Scanning Calorimetry (DSC) and used to formulate edible films. The developed edible films are characterized based on their physicochemical and mechanical properties. The physicochemical and functional properties of starch are affected by the incorporation of the acyl and acetyl group. Both starches exhibit a significant decrease in solubility. Starch modified by the incorporation of the acyl group (lauroyl) has higher thermal stability than starch modified by the incorporation of the acetyl group. The first shows an increase in emulsifying and foaming capacity, as well as water‐ and oil‐retention capacity, while the second exhibits adequate edible film‐forming properties. The edible films develop with modified starch with acetyl group has a homogeneous surface and exhibit a higher percentage of elongation at break when they are stored at a water activity of 0.561. In accordance with the above, it is concluded that the chayote root starch modified has physicochemical and functional properties that indicate their potential utility in the food industry. [ABSTRACT FROM AUTHOR]

The kinetics of nucleophilic substitution reactions involving 2,4‐dinitrophenyl 5‐substituted‐2‐thiophenecarboxylate were studied kinetically with 4‐Z‐C6H4O−/4‐Z‐C6H4OH, which facilitated the reactions, in 20 mol% DMSO(aq). The reactions followed second‐order kinetics and exhibited βacyl = −2.34 to −2.92, ρ(Y) = 2.71–3.39, βnuc = 0.74–0.83, and |βlg| = 0.40–0.57. Based on the interpretation of the results, we have concluded that the reaction follows an addition–elimination mechanism in which the first step is the rate‐determining step (rds). The transition state structures for the 4‐ZC6H4O−‐promoted reactions remained nearly the same with a change in the leaving group from 4‐nitrophenoxide to 2,4‐dinitrophenoxide. The mechanism of the 4‐ZC6H4O−‐promoted reaction was similar to that of R2NH‐promoted reactions, except that the former proceeded with the 1st step being the rds and the latter proceeded with a change in the rds from the second to the first step with a stronger nucleophile. [ABSTRACT FROM AUTHOR]

A single acyloxy group at C‐2 can control the outcome of nucleophilic substitution reactions of pyran‐derived acetals, but the extent of the neighboring‐group participation depends on a number of factors. We show here that neighboring‐group participation does not necessarily control the stereochemical outcome of acetal substitution reactions with weak nucleophiles. The 1,2‐trans selectivity increased with increasing reactivity of the incoming nucleophile. This trend suggests the intermediacy of both cis‐fused dioxolenium ions and oxocarbenium ions in the stereochemistry‐determining step. In addition, as the electron‐donating ability of the neighboring group decreased, the preference for the 1,2‐trans products increased. Computational studies show how the barriers for the ring‐opening reaction on the dioxolenium ions and the transition states to provide the oxocarbenium ions change with the electron‐donating capacity of the C‐2‐acyloxy group and the reactivity of the nucleophile. [ABSTRACT FROM AUTHOR]

Isoquinolones and isoquinolines are crucial natural and synthetic heterocyclic compounds exhibiting a range of biological activities. A less explored strategy for the recyclization of isocoumarins to isoquinolones involves the transformation of 1H‐isochromen‐1‐ones with a carbonyl group at position 3 using primary amines. This study presents a straightforward one‐pot protocol for the recyclization of 3‐acetyl‐ and 3‐benzoylisocoumarins into their corresponding isoquinolone derivatives using structurally diverse primary amines. This provides versatile and scalable routes for accessing a variety of 2‐R‐isoquinolin‐1(2H)‐ones. Interestingly, the acyl group also reacted with the hydroxyl group of 2‐aminoethanol, leading to the simultaneous formation of 3,4‐dihydro[1,4]oxazino[4,3‐b]isoquinolin‐6(1H)‐ones alongside lactone recyclization. Moreover, the recyclization process was accompanied by more complex alternative cyclizations, including an oxidative‐reductive stage. For instance, the recyclization of isocoumarins with benzylamine resulted in the formation of isochromeno[3,4‐c]pyrroles, whereas with glycine derivatives, 1,2‐dihydro‐6H‐pyrazino[1,2‐b]isoquinolin‐3,6(4H)‐diones were obtained. [ABSTRACT FROM AUTHOR]

Synthesis of bicyclic scaffolds has attracted tremendous attention because they are playing an important role as saturated bioisosteres of benzenoids in modern drug discovery. Here, we report a BF3‐catalyzed [2π+2σ] cycloaddition of aldehydes with bicyclo[1.1.0]butanes (BCBs) to access polysubstituted 2‐oxabicyclo[2.1.1]hexanes. A new kind of BCB containing an acyl pyrazole group was invented, which not only significantly facilitates the reactions, but can also serve as a handle for diverse downstream transformations. Furthermore, aryl and vinyl epoxides can also be utilized as substrates which undergo cycloaddition with BCBs after in situ rearrangement to aldehydes. We anticipate that our results will promote access to challenging sp3‐rich bicyclic frameworks and the exploration of BCB‐based cycloaddition chemistry. [ABSTRACT FROM AUTHOR]

Acyl group migration has been the subject of several studies. Such migration processes may cause problems during synthesis, isolation, and purification of different acyl‐bearing compounds, and have biological relevance, for example, in the metabolism of pharmaceuticals. Considering the recent evidence of acyl group migration being possible even over glycosidic bonds, it could be hypothesized to be involved also in the regulation of biological activity of natural polysaccharides in the host cells. Migrations are mostly observed in carbohydrates, typically having several hydroxyl groups near each other. Several studies have investigated the migration in a single or only a few different carbohydrate molecules, providing different suggestions for the mechanisms of migration, seldom supported by comprehensive computational investigations. In this concept article we discuss the recent progress on the mechanistic aspects of acyl group migration, with carbohydrates in particular focus. [ABSTRACT FROM AUTHOR]

In order to improve the thermal stability of perovskite solar cells (PSCs) and reduce production costs, hole transport layer (HTL)‐free carbon‐based CsPbI3 PSCs (C‐PSCs) have attracted the attention of researchers. However, the power conversion efficiency (PCE) of HTL‐free CsPbI3 C‐PSCs is still lower than that of PSCs with HTL/ metal electrodes. This is because the direct contact between the carbon electrode and the perovskite layer has a higher requirement on the crystal quality of perovskite layer and matched energy level at perovskite/carbon interface. Herein, the acyl chloride group and its derivative trichloroacetyl chloride are used to passivate CsPbI3 C‐PSCs for the first time. The results show that the carbonyl group of trichloroacetyl chloride can effectively passivate the uncoordinated Pb2+ ions in perovskite. At the same time, leaving group Cl− ions can increase the grain size of perovskite and improve the crystallization quality of perovskite layer. In addition, the trichloroacetyl chloride tends to generate cesium chloride acetate, which acts as an electron blocking layer, reduces charge recombination, promotes gradient energy level arrangement, and effectively improves the separation and extraction ability of carriers. The PCE of CsPbI3 HTL‐free C‐PSCs is successfully increased from 13.40% to 14.82%. [ABSTRACT FROM AUTHOR]

A simple method for the synthesis of cyclopropane compounds via cross‐coupling reaction between tertiary cyclopropyl carbagermatranes and acyl chlorides was reported. Derivatives of acryloyl chloride and aliphatic acyl chloride also performed to be suitable substrates. This process can be used to introduce a wide range of functionalized cyclopropane groups and acyl groups directly. [ABSTRACT FROM AUTHOR]

We developed a route to rhodomyrtone analogs that feature different acyl groups at C7. Since electrophilic substitution reactions on the aryl part of the rhodomyrtone core led to C5 derivatives, the C5 position was blocked by a chlorine. Subsequent Duff type formylation followed by Grignard addition to the aldehyde group and oxidation gave various phenones. The benzyl protecting groups were removed by hydrogenation or boron tribromide. Some derivatives turned out to be quite active against multiple resistant Staphylococcus aureus strains and a rhodomyrtone resistant mutant (RomR). The chlorine at C5 seems to have a beneficial effect on the antibacterial activity. [ABSTRACT FROM AUTHOR]

"Through space" palladium/hydrogen shift is an efficient strategy to achieve selective functionalization of a specific remote C−H bond. Compared with relatively extensive exploited 1,4‐palladium migration process, the relevant 1,5‐Pd/H shift was far less investigated. We herein report a novel 1,5‐Pd/H shift pattern between a vinyl and an acyl group. Through the pattern, rapid access to 5‐membered‐dihydrobenzofuran and indoline derivatives has been achieved. Further studies have unveiled an unprecedented trifunctionalization (vinylation, alkynylation and amination) of a phenyl ring through 1,5‐palladium migration relayed decarbonylative Catellani type reaction. A series of mechanistic investigations and DFT calculations have provided insights into the reaction pathway. Notably, it was unveiled that the 1,5‐palladium migration in our case prefers a stepwise mechanism involving a PdIV intermediate. [ABSTRACT FROM AUTHOR]

"Through space" palladium/hydrogen shift is an efficient strategy to achieve selective functionalization of a specific remote C−H bond. Compared with relatively extensive exploited 1,4‐palladium migration process, the relevant 1,5‐Pd/H shift was far less investigated. We herein report a novel 1,5‐Pd/H shift pattern between a vinyl and an acyl group. Through the pattern, rapid access to 5‐membered‐dihydrobenzofuran and indoline derivatives has been achieved. Further studies have unveiled an unprecedented trifunctionalization (vinylation, alkynylation and amination) of a phenyl ring through 1,5‐palladium migration relayed decarbonylative Catellani type reaction. A series of mechanistic investigations and DFT calculations have provided insights into the reaction pathway. Notably, it was unveiled that the 1,5‐palladium migration in our case prefers a stepwise mechanism involving a PdIV intermediate. [ABSTRACT FROM AUTHOR]

Multiblock copolymers are envisioned as promising materials with enhanced properties and functionality compared with their diblock/triblock counterparts. However, the current approaches can construct multiblock copolymers with a limited number of blocks but tedious procedures. Here, we report a thioester‐relayed in‐chain cascade copolymerization strategy for the easy preparation of multiblock copolymers with on‐demand blocks, in which thioester groups with on‐demand numbers are built in the polymer backbone by controlled/living polymerizations. These thioester groups further serve as the in‐chain initiating centers to trigger the acyl group transfer ring‐opening polymerization of episulfides independently and concurrently to extend the polymer backbone into multiblock structures. The compositions, number of blocks, and block degree of polymerization can be easily regulated. This strategy can offer easy access to a library of multiblock copolymers with ≈100 blocks in only 2 to 4 steps. [ABSTRACT FROM AUTHOR]

Multiblock copolymers are envisioned as promising materials with enhanced properties and functionality compared with their diblock/triblock counterparts. However, the current approaches can construct multiblock copolymers with a limited number of blocks but tedious procedures. Here, we report a thioester‐relayed in‐chain cascade copolymerization strategy for the easy preparation of multiblock copolymers with on‐demand blocks, in which thioester groups with on‐demand numbers are built in the polymer backbone by controlled/living polymerizations. These thioester groups further serve as the in‐chain initiating centers to trigger the acyl group transfer ring‐opening polymerization of episulfides independently and concurrently to extend the polymer backbone into multiblock structures. The compositions, number of blocks, and block degree of polymerization can be easily regulated. This strategy can offer easy access to a library of multiblock copolymers with ≈100 blocks in only 2 to 4 steps. [ABSTRACT FROM AUTHOR]

A photochemical cyclization of F‐tagged, o‐alkynylated N‐alkylamides to indoles catalyzed by [Ir(dF(CF3)ppy)2(dtbpy)]PF6 is presented. This straightforward and efficient reaction involves an intramolecular rearrangement due to the presence of an electron withdrawing group in the acyl moiety and is the first example of photochemically induced 1,3‐acyl shift in the cyclization towards 3‐acylindoles. A four‐step reaction sequence including the photoreaction as a key step to the desired indoles has been developed and optimized. The compatibility of differently substituted F‐tagged precursors with the photocyclization step was investigated and the robustness of this step towards modifications could be shown. In total, 16 so far unknown derivatives with diverse modifications in positions N1 and C2, bearing a pentadecafluorooctanoyl moiety as F‐tag, were synthesized in very good yields and fully characterized. [ABSTRACT FROM AUTHOR]

Taxol is a clinically used drug for the treatment of various types of cancers. Its 6/8/6/4‐membered ring (ABCD‐ring) system is substituted by eight oxygen functional groups and flanked by four acyl groups, including a β‐amino acid side chain. Here we report a 34‐step total synthesis of this unusually oxygenated and intricately fused structure. Inter‐ and intramolecular radical coupling reactions connected the A‐ and C‐ring fragments and cyclized the B‐ring, respectively. Functional groups of the A‐ and C‐rings were then efficiently decorated by employing newly developed chemo‐, regio‐, and stereoselective reactions. Finally, construction of the D‐ring and conjugation with the β‐amino acid delivered taxol. The powerful coupling reactions and functional group manipulations implemented in the present synthesis provide new valuable information for designing multistep target‐oriented syntheses of diverse bioactive natural products. [ABSTRACT FROM AUTHOR]

Taxol is a clinically used drug for the treatment of various types of cancers. Its 6/8/6/4‐membered ring (ABCD‐ring) system is substituted by eight oxygen functional groups and flanked by four acyl groups, including a β‐amino acid side chain. Here we report a 34‐step total synthesis of this unusually oxygenated and intricately fused structure. Inter‐ and intramolecular radical coupling reactions connected the A‐ and C‐ring fragments and cyclized the B‐ring, respectively. Functional groups of the A‐ and C‐rings were then efficiently decorated by employing newly developed chemo‐, regio‐, and stereoselective reactions. Finally, construction of the D‐ring and conjugation with the β‐amino acid delivered taxol. The powerful coupling reactions and functional group manipulations implemented in the present synthesis provide new valuable information for designing multistep target‐oriented syntheses of diverse bioactive natural products. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Group B Streptococcus (GBS) is the major pathogen that causes invasive infectious diseases in neonates and infants. The development of preventive and therapeutic strategies against GBS infection has been becoming the most pressing subject worldwide. Group B carbohydrate (GBC), the group B‐specific polysaccharide that distinguishes GBS with other streptococci species, has been identified as an attractive antigen for diagnosis and vaccine development because of its highly conservative tetra‐antennary structure. In this paper, a highly convergent [3 + 5] glycosylation strategy for efficient synthesis of an octasaccharide derivative related to GBC oligosaccharide unit II has been developed. In this synthesis, each glycosylation reaction was efficiently constructed with glycosyl imidates, especially trifluoroacetimidate, as donors, and each glycosidic bond was stereoselectively controlled via the neighboring group participation effect of acyl group on the 2‐O‐position of imidate donors or the solvent effect of Et2O. Furthermore, the aminoethylphosphate group was smoothly installed on the 6‐O‐position of d‐glucitol residue using the phosphoramidite method. After global deprotection, the target octasaccharide was successfully obtained from d‐glucitol in 29 steps with an overall yield of 1.37%. The free amino group installed on the aminoethylphosphate spacer of the target molecule enables its modification with functionalized biomolecules for further biological studies. [ABSTRACT FROM AUTHOR]

Herein, a three component Catellani‐type reaction catalyzed by the Palladium/Norbornene/CuI (Pd/NBE/CuI) cooperative system by using N‐acylph‐thalimides as acyl electrophiles is reported, which gives access to a series of aromatic ketones. The transformation is performable in the presence of water, albeit with decreased reaction yield. The additive CuI was crucial to facilitate the cleavage of C(O)−N bond of imide. This protocol showed broad substrate scope: both alkyl and aryl acyl groups could be installed at the ortho‐position of aryl iodides; alkenes and boronic acids can be used as termination reagents. [ABSTRACT FROM AUTHOR]

Palladium(II) hydroxide on carbon is a catalyst routinely used for the cleavage of O‐benzyl groups by hydrogenolysis to obtain the corresponding parent organic compound. The work described in this article shows that allyl and benzyl phosphates, can be cleaved efficiently and selectively using palladium(II) hydroxide on carbon, under non‐hydrogenolytic and neutral conditions, precluding the migration of acyl groups. The utility of these cleavage reactions for the synthesis of diacylglycerol and phosphatidic acid, containing unsaturation, is demonstrated. These methods have high potential for the synthesis of a variety of phosphates and natural phospholipids. [ABSTRACT FROM AUTHOR]

Acyl group migration affects the synthesis, isolation, manipulation and purification of all acylated organic compounds containing free hydroxyl groups, in particular carbohydrates. While several isolated studies on the migration phenomenon in different buffers have been reported, comprehensive insights into the overall migration process in different monosaccharides under similar conditions have been lacking. Here, we have studied the acyl migration in different monosaccharides using five different acyl groups by a combination of experimental, kinetic and theoretical tools. The results show that the anomeric configuration in the monosaccharide has a major influence on the migration rate, together with the relative configurations of the other hydroxyl groups and the nature of the migrating acyl group. Full mechanistic model, based on computations, demonstrates that the acyl migration proceeds through an anionic stepwise mechanism with linear dependence on the [OH−] and the pKa of the hydroxyl group toward which the acyl group is migrating. [ABSTRACT FROM AUTHOR]

Acyl phosphines (R2P–C(O)R) are the tertiary phosphorus compounds having a P–C(O) linkages. Though they are known historically, their literature is not exhaustive mainly due to the vulnerability of P–C(O) bonds toward nucleophilic substitution reactions. However, there is a renewed interest in the synthesis of acyl phosphines and di (acyl) phosphines, recently. Among the methods available for the synthesis, most involve nucleophilic substitutions at carbonyl carbon by phosphorus nucleophile as a customary step. The examples of phosphines possessing two acyl groups (R(O)C–RP–C(O)R) are found more frequently in the literature of late, and most of them are cyclic in nature. The transition‐metal complexes of acyl phosphines and di (acyl) phosphines are moderately explored in literature. However, their catalytic applications are meager. In the current review, the details of syntheses, reactivity, structural features, and catalytic activities of acyl phosphines and bis (acyl) phosphines reported in the last three decades are discussed. [ABSTRACT FROM AUTHOR]

Summary: The metabolic flux of fatty acyl‐CoAs determines lipopeptide biosynthesis efficiency, because acyl donor competition often occurs from polyketide biosynthesis and homologous pathways. We used A40926B0 as a model to investigate this mechanism. The lipopeptide A40926B0 with a fatty acyl group is the active precursor of dalbavancin, which is considered as a new lipoglycopeptide antibiotic. The biosynthetic pathway of fatty acyl‐CoAs in the A40926B0 producer Nonomuraea gerenzanensis L70 was efficiently engineered using endogenous replicon CRISPR (erCRISPR). A polyketide pathway and straight‐chain fatty acid biosynthesis were identified as major competitors in the malonyl‐CoA pool. Therefore, we modified both pathways to concentrate acyl donors for the production of the desired compound. Combined with multiple engineering approaches, including blockage of an acetylation side reaction, overexpression of acetyl‐CoA carboxylase, duplication of the dbv gene cluster and optimization of the fermentation parameters, the final strain produced 702.4 mg l‐1 of A40926B0, a 2.66‐fold increase, and the ratio was increased from 36.2% to 81.5%. Additionally, an efficient erCRISPR‐Cas9 editing system based on an endogenous replicon was specifically developed for L70, which increased conjugation efficiency by 660% and gene‐editing efficiency was up to 90%. Our strategy of redirecting acyl donor metabolic flux can be widely adopted for the metabolic engineering of lipopeptide biosynthesis. [ABSTRACT FROM AUTHOR]

We developed a chiral symmetry breaking method for monoacylated meso diols. The X‐ray crystal structure analysis of monoacylated 1,4‐anhydroerythritols, meso cyclic diols with a cis configuration, revealed that the O‐(p‐anisoyl) derivative crystallized as a racemic conglomerate of the P212121 crystal system. It was confirmed that the substrate racemized by intramolecular transfer of the acyl group in the presence of a catalytic amount of base. Evaporating the solvent gradually from the solution or Viedma ripening to promote crystallization‐induced deracemization efficiently led to enantiomer crystals. These results provide the first successful example of asymmetric expression and amplification by deracemization of sugar derivatives without an external chemical chiral source. Furthermore, we applied this methodology to acyclic meso‐1,2‐diols. Three O‐monoacylated substrates were successfully deracemized to 99 % ee by Viedma ripening. We also developed asymmetric desymmetrization of meso‐1,2‐diols by combining acylation and crystallization‐induced deracemization. [ABSTRACT FROM AUTHOR]

We developed a chiral symmetry breaking method for monoacylated meso diols. The X‐ray crystal structure analysis of monoacylated 1,4‐anhydroerythritols, meso cyclic diols with a cis configuration, revealed that the O‐(p‐anisoyl) derivative crystallized as a racemic conglomerate of the P212121 crystal system. It was confirmed that the substrate racemized by intramolecular transfer of the acyl group in the presence of a catalytic amount of base. Evaporating the solvent gradually from the solution or Viedma ripening to promote crystallization‐induced deracemization efficiently led to enantiomer crystals. These results provide the first successful example of asymmetric expression and amplification by deracemization of sugar derivatives without an external chemical chiral source. Furthermore, we applied this methodology to acyclic meso‐1,2‐diols. Three O‐monoacylated substrates were successfully deracemized to 99 % ee by Viedma ripening. We also developed asymmetric desymmetrization of meso‐1,2‐diols by combining acylation and crystallization‐induced deracemization. [ABSTRACT FROM AUTHOR]

Fluorination is a potent method to modulate chemical properties of glycans. Here, we study how C3‐ and C6‐fluorination of glucosyl building blocks influence the structure of the intermediate of the glycosylation reaction, the glycosyl cation. Using a combination of gas‐phase infrared spectroscopy and first‐principles theory, glycosyl cations generated from fluorinated and non‐fluorinated monosaccharides are structurally characterized. The results indicate that neighboring group participation of the C2‐benzoyl protecting group is the dominant structural motif for all building blocks, correlating with the β‐selectivity observed in glycosylation reactions. The infrared signatures indicate that participation of the benzoyl group in enhanced by resonance effects. Participation of remote acyl groups such as Fmoc or benzyl on the other hand is unfavored. The introduction of the less bulky fluorine leads to a change in the conformation of the ring pucker, whereas the structure of the active dioxolenium site remains unchanged. [ABSTRACT FROM AUTHOR]

An efficient and straightforward methodology for the esterification of various N‐heteroarene methanols using benzoyl cyanides as acylating sources through a simply mixing conditions has been reported. The acyl groups were in‐situ generated via chemoselective C–CN bond cleavage to give the N‐heteroarenemethyl esters. This process features in readily accessible starting materials and offers an easy operational procedure, and broad substrate scope with excellent selectivity. [ABSTRACT FROM AUTHOR]

The stereoselective introduction of the glycosidic bond remains one of the main challenges in carbohydrate synthesis. Characterizing the reactive intermediates of this reaction is key to develop stereoselective glycosylation reactions. Herein we report the characterization of low‐populated, rapidly equilibrating mannosyl dioxanium ions that arise from participation of a C‐3 acyl group using chemical exchange saturation transfer (CEST) NMR spectroscopy. Dioxanium ion structure and equilibration kinetics were measured under relevant glycosylation conditions and highly α‐selective couplings were observed suggesting glycosylation took place via this elusive intermediate. [ABSTRACT FROM AUTHOR]

Mitochondrial cristae are extraordinarily crowded with proteins, which puts stress on the bilayer organization of lipids. We tested the hypothesis that the high concentration of proteins drives the tafazzin‐catalyzed remodeling of fatty acids in cardiolipin, thereby reducing bilayer stress in the membrane. Specifically, we tested whether protein crowding induces cardiolipin remodeling and whether the lack of cardiolipin remodeling prevents the membrane from accumulating proteins. In vitro, the incorporation of large amounts of proteins into liposomes altered the outcome of the remodeling reaction. In yeast, the concentration of proteins involved in oxidative phosphorylation (OXPHOS) correlated with the cardiolipin composition. Genetic ablation of either remodeling or biosynthesis of cardiolipin caused a substantial drop in the surface density of OXPHOS proteins in the inner membrane of the mouse heart and Drosophila flight muscle mitochondria. Our data suggest that OXPHOS protein crowding induces cardiolipin remodelling and that remodeled cardiolipin supports the high concentration of these proteins in the inner mitochondrial membrane. SYNOPSIS: In mitochondrial cristae, proteins are packaged at uniquely high density, imposing stress on the membrane lipid composition. This work uncovers acyl group remodeling of the membrane phospholipid cardiolipin as a precondition for concentrating oxidative phosphorylation (OXPHOS) proteins in the inner mitochondrial membrane. Protein crowding affects fatty acid remodeling of cardiolipin in vitro.The surface concentration of OXPHOS proteins correlates with the molecular species composition of cardiolipin.Ablation of cardiolipin remodeling or biosynthesis decreases surface concentration of OXPHOS proteins in mice and flies. [ABSTRACT FROM AUTHOR]

Natural product synthesis has been the prime focus for the development of new carbon‐carbon bond forming transformations. In particular, the construction of molecules with all‐carbon quaternary centers remain one of the most facinating targets. In this regard, transition‐metal catalyzed processes have gained imporatnce owing to their mild nature. Towards this, Pd(0)‐catalyzed decarboxylative allylations (DcA) is worth mentioning and has emerged as a convenient method for synthesis of molecules even in their enantioenriched form. However, in order to have a flexible approach that facilitate rapid production of derivatives by utilizing commercially available allyl alcohols, the concept of Pd(0)‐catalyzed deacylative allylations (DaA) methodology gains popularity. In these reactions, the transfer of an acyl group has a functional role in activating the allylic alcohol (proelectrophile) toward reaction with Pd(0)‐catalysts. We present here an Account on newly conceptualized deacylative allylations (DaA) methodology and its applications in the synthesis of various intermediates and building blocks. Further, its potential in the total synthesis of naturally occurring alkaloids have been summarized in this personal account. [ABSTRACT FROM AUTHOR]

Phlorofucofuroeckol‐A (PFF‐A) is a phlorotannin extracted from various brown algae. PFF‐A shows low toxicity when ingested and various biochemical effects, including antioxidant, anti‐inflammatory, anti‐cancer, and anti‐allergy properties. In this study, various di‐O‐substituted PFF‐A derivatives were synthesized by introducing alkyl or acyl groups at two specific hydroxyls out of the nine nearly equivalent phenolic OH groups present in PFF‐A. The exact molecular structures of the synthesized derivatives were analyzed using two‐dimensional nuclear magnetic resonance (2D NMR) spectroscopy, which confirmed that the substituents were regioselectively introduced at the 1OH and 6OH positions. Small amounts of three mono‐O‐substituted derivatives were generated as by‐products in this reaction, and their structures and regioselectivity were determined using 2D NMR spectroscopy. This study can provide insights into understanding the mechanism of action of eckol‐based compounds and developing new drug candidates. [ABSTRACT FROM AUTHOR]

A serious of C4‐position aniline functionalized 5H‐pyrano[2,3‐d]pyrimidine derivatives were synthesized from the corresponding chlorinated pyrimidines and acetanilides. This process was approached by treating the acetanilide with NaH instead of aniline, where a dissociation of the acyl group in situ happened during the reaction. The strategy worked out the non‐reactive route resulted from the low reactivity of aniline. This C−N bond formation features mild reaction conditions, simple execution, and broad substrate scope. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: Developing an effective chemoselective ligation strategy for assembling unprotected peptide segments is important to peptide/protein synthesis. The ligation efficiency and selectivity depend on the chemistry between the C‐terminal active ester of the peptide (e.g., the thioester in Native Chemical Ligation or the salicylaldehyde ester in Ser/Thr Ligation and Cys/Pen Ligation) and N‐terminal functional groups of the second peptide (Cys or Ser/Thr). Increasing the reactivity of the ligation and decreasing the hydrolysis of the active ester are more like the opposite sites in balance. We investigated the potential application of the peptide acyl ester of 2‐formylphenylboronic acid (2‐FPBA) in the Ser/Thr ligation and Cys/Pen ligation. With the assistance of boronic acid group, the peptidyl FPBA ester showed remarkable stability in aqueous buffer and its reactivity towards Ser/Thr and Cys/Pen also improved. However, the strong coordination of the amine at the N‐terminus and boronic acid suppressed the acyl transfer process when the peptide acyl group was used. More effects should be made to enhance the ligation chemistry. [ABSTRACT FROM AUTHOR]

A method is described for the isomerization of acyclic allylic alcohols into β‐functionalized ketones via 1,3‐alkyl transposition. This reaction proceeds via light‐driven proton‐coupled electron transfer (PCET) activation of the O−H bond in the allylic alcohol substrate, followed by C−C β‐scission of the resulting alkoxy radical. The transient alkyl radical and enone acceptor generated in the scission event subsequently recombine via radical conjugate addition to deliver β‐functionalized ketone products. A variety of allylic alcohol substrates bearing alkyl and acyl migratory groups were successfully accommodated. Insights from mechanistic studies led to a modified reaction protocol that improves reaction performance for challenging substrates. [ABSTRACT FROM AUTHOR]

A method is described for the isomerization of acyclic allylic alcohols into β‐functionalized ketones via 1,3‐alkyl transposition. This reaction proceeds via light‐driven proton‐coupled electron transfer (PCET) activation of the O−H bond in the allylic alcohol substrate, followed by C−C β‐scission of the resulting alkoxy radical. The transient alkyl radical and enone acceptor generated in the scission event subsequently recombine via radical conjugate addition to deliver β‐functionalized ketone products. A variety of allylic alcohol substrates bearing alkyl and acyl migratory groups were successfully accommodated. Insights from mechanistic studies led to a modified reaction protocol that improves reaction performance for challenging substrates. [ABSTRACT FROM AUTHOR]

Efficient methods for the synthesis of fluorinated compounds have been intensively studied, recently. Development of practical fluorinating reagents is indispensable for this purpose. Herein, bench‐stable electrophilic fluorinating reagents were synthesized as N‐fluorobenzenesulfonimide (NFSI) substitutes. Reagents obtained by replacing one of the NFSI sulfonyl groups with an acyl group led to the highly selective monofluorination of silyl enol ethers with suppression of undesired overreaction, that is, difluorination. On the other hand, reagents bearing electron‐withdrawing substituents at NFSI benzenesulfonyl groups efficiently facilitated the difluorination of silyl enol ethers under base‐free conditions. Thus, both mono‐ and difluorinated target materials were prepared from the same substrate. [ABSTRACT FROM AUTHOR]

Reactions in solids are of contemporary interest due to applications in pharmaceutical industries to environmental sustainability. Although several reactive crystals that support chemical reactions have been identified and characterized, the same cannot be said about reactive cocrystals. Earlier we correlated the facile acyl group transfer reactions in crystals with supramolecular parameters obtained from the crystal structures. The structure‐reactivity correlation revealed the requirement of proper juxtaposition of electrophile (C=O) and the nucleophile (OH) with distance (∼3.2 Å) and angle (∼90°) along the chain structure. The current article describes the preparation of cocrystals that are capable of supporting intermolecular acyl group transfer reactions in a group of structurally similar molecules. The cocrystals of naphthalene 2,3‐diol and its corresponding diesters showed a facile solid state acyl transfer reaction, which has been well correlated with their crystal structures. [ABSTRACT FROM AUTHOR]

Reactions of 4‐nitrophenyl 2‐furoates (1a–e) with R2NH/R2NH2+ in 20 mol% DMSO(aq) have been studied. The reactions produced aminolysis products and exhibited second‐order kinetics. The Brönsted plots were linear with βnuc values of 0.75–0.89, which remained nearly the same for all 5‐furyl substituents. The rate data showed excellent correlations on the Yukawa‐Tsuno plots with ρ(x) = 0.72–1.1, and r = 0.55–0.95, respectively. The ρ value increased and r value decreased with a stronger nucleophile, indicating an increase in the electron density at the CO bond and a decrease in the resonance contribution. The results have been interpreted with the addition–elimination mechanism in which the second step is the rds. By comparing with the data for ArC(O)OC6H4‐4‐NO2 (Ar = Ph, thienyl), the effect of the aryl group on the acyl transfer reaction was assessed. [ABSTRACT FROM AUTHOR]

Gold‐catalyzed reactions of alkynyl N‐sulfinylimines were used to produce the corresponding 2H‐azirines possessing sulfenyl and acyl groups at the 3‐position of the azirine ring in good to excellent yields. These reactions involved internal transfer of the sulfinyl oxygen atom to form a thiooxime intermediate tethered to an α‐oxo gold carbene moiety. Subsequent insertion of the carbene into the N−S bond resulted in ring construction. [ABSTRACT FROM AUTHOR]

Gold‐catalyzed reactions of alkynyl N‐sulfinylimines were used to produce the corresponding 2H‐azirines possessing sulfenyl and acyl groups at the 3‐position of the azirine ring in good to excellent yields. These reactions involved internal transfer of the sulfinyl oxygen atom to form a thiooxime intermediate tethered to an α‐oxo gold carbene moiety. Subsequent insertion of the carbene into the N−S bond resulted in ring construction. [ABSTRACT FROM AUTHOR]

Acylcarnitines are a big family of small molecule metabolites with various acyl groups attached to the hydroxyl moiety of l‐carnitine. They are good indicators of multiple metabolic disorders. For instance, the newborn screening panel uses flow injection tandem mass spectrometry to analyze more than 30 different acylcarnitines and amino acids extracted from dried blood spots. A facile approach has been developed for the synthesis of isotope labeled acylcarnitines whose mass shift over their unlabeled counterparts can be any number in the range of 3 to 12 Da. This strategy makes it more convenient to provide authentic internal standards for acylcarnitines profiling analyses, thereby expanding their clinical applications. [ABSTRACT FROM AUTHOR]

Herein, we report the nickel‐catalyzed cascade C−O bond cleavage/cyclization of ortho‐alkynylphenyl ester to construct a 3‐acylbenzo[b]furan skeleton. As a result of reaction condition screening, the Ni(0)/IAd (1,3‐Di(1‐adamantyl)imidazole‐2‐ylidene) system was found to be optimal for catalytic conversion. Interestingly, the reaction exclusively gives 3‐acylbenzo[b]furan instead of a decarbonylated product frequently observed in reactions mediated by acyl‐nickel species. The catalyst loadings could be reduced to 5–10 mol %. We demonstrated the synthesis of a variety of functionalized 3‐acylbenzofuran derivatives. We conducted stoichiometric study of nickel complexes as well as density functional theory (DFT) calculations to support a possible reaction mechanism. [ABSTRACT FROM AUTHOR]

Rearrangement reactions incorporated into cascade reactions play an important role in rapidly increasing molecular complexity from readily available starting materials. Reported here is a Cu‐catalyzed cascade reaction of α‐(hetero)aryl‐substituted alkyl (hetero)aryl ketones with primary amines that incorporates an unusual 1,2‐aryl migration induced by amide C−N bond formation to produce a class of structurally novel α,α‐diaryl β,γ‐unsaturated γ‐lactams in generally good‐to‐excellent yields. This cascade reaction has a broad substrate scope with respect to primary amines, allows a wide spectrum of (hetero)aryl groups to smoothly undergo 1,2‐migration, and tolerates electronically diverse α‐substituents on the (hetero)aryl ring of the ketones. Mechanistically, this 1,2‐aryl migration may stem from the intramolecular amide C−N bond formation which induces nucleophilic migration of the aryl group from the acyl carbon center to the electrophilic carbon center that is conjugated with the resulting iminium moiety. [ABSTRACT FROM AUTHOR]

Rearrangement reactions incorporated into cascade reactions play an important role in rapidly increasing molecular complexity from readily available starting materials. Reported here is a Cu‐catalyzed cascade reaction of α‐(hetero)aryl‐substituted alkyl (hetero)aryl ketones with primary amines that incorporates an unusual 1,2‐aryl migration induced by amide C−N bond formation to produce a class of structurally novel α,α‐diaryl β,γ‐unsaturated γ‐lactams in generally good‐to‐excellent yields. This cascade reaction has a broad substrate scope with respect to primary amines, allows a wide spectrum of (hetero)aryl groups to smoothly undergo 1,2‐migration, and tolerates electronically diverse α‐substituents on the (hetero)aryl ring of the ketones. Mechanistically, this 1,2‐aryl migration may stem from the intramolecular amide C−N bond formation which induces nucleophilic migration of the aryl group from the acyl carbon center to the electrophilic carbon center that is conjugated with the resulting iminium moiety. [ABSTRACT FROM AUTHOR]

The temperature‐dependent phase transition behavior of acetylated polyrotaxanes (PRXs) consisting of acylated α‐cyclodextrins threaded onto a poly(ethylene glycol) chain in an aqueous solution is investigated. Acetyl (Ac), propionyl (Pr), and butyryl (Bu) group‐modified PRXs with different degrees of substitution are synthesized to elucidate the effect of the alkyl chain length of the acyl groups on temperature responsivity. Ac‐PRXs, Pr‐PRXs, and Bu‐PRXs are dissolved in water and exhibit temperature‐dependent transmittance changes accompanied by coacervate formation. However, the temperature responsivity of acylated PRXs is seen in limited degree of substitution range (≈10%). The maximum degree of substitution to show temperature responsivity of acylated PRXs decreases with increasing alkyl chain length of the acyl groups. Transmittance measurements of acylated PRXs in the presence of urea reveal that the alkyl chain length of the acyl groups determines the predominant force involved in the temperature‐induced phase transition. During the temperature‐induced phase transition of Pr‐PRXs and Bu‐PRXs, hydrophobic interactions are predominant; however, hydrogen bond formation may occur in Ac‐PRXs. These fundamental findings related to acylated PRXs will facilitate the application of PRXs as thermoresponsive supramolecular materials. [ABSTRACT FROM AUTHOR]