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A palladium‐catalyzed highly C−S‐selective Stille cross‐coupling between aryl thianthrenium salts and tri‐ or tetrasubstituted alkenyl stannanes is described. Herein, critical challenges including site‐ and chemoselectivity control are well addressed through C−H thianthrenation and C−S alkenylation, thereby providing an expedient access to stereodefined tri‐ and tetrasubstituted alkenes in a stereoretentive fashion. Indeed, the palladium‐catalyzed Stille‐alkenylation of poly(pseudo)halogenated arenes displays privileged capability to differentiate C−S over C−I, C−Br, C−Cl bonds, as well as oxygen‐based triflates (C−OTf), tosylates (C−OTs), carbamates and sulfamates under mild reaction conditions. Sequential and multiple cross‐couplings via selective C−X functionalization should be widely applicable for increasing functional molecular complexity. Modular installation of stereospecific alkene motifs into pharmaceuticals illustrated the synthetic application of the present protocol in drug discovery. [ABSTRACT FROM AUTHOR]

The isoindigo and its derivatives have rapidly garnered attention as widely employed electron‐deficient moieties, finding extensive applications in organic field‐effect transistors. In this study, four different isoindigo‐based organic semiconductor polymers were synthesized via a Stille coupling reaction of four isoindigo molecules with varying side chains serving as acceptors and bithiophene as donors. Furthermore, their optical, electrochemical, thermal stability, and other relevant properties were comprehensively evaluated. These polymers exhibited remarkable electrochemical and thermal stability attributed to their low LUMO energy level, which facilitates effective electrical contact between the semiconductor layer and the source/drain while ensuring excellent air stability for the semiconductor polymers. Additionally, solution‐gate field‐effect transistors prepared using these polymers achieved hole mobilities of 10−2 cm2 V−1 S−1 along with an Ion/Ioff ratio of 8.39×103, demonstrating exceptional field‐effect performance. [ABSTRACT FROM AUTHOR]

Abstract The oxygenated sesquiterpenoid (‐)‐integrifolian‐1,5‐dione, which originates from a plant that finds widespread use in South American traditional medicine, is distinguished by a rigid bicyclic framework consisting of a cyclopropane that is cis‐annulated to a cyclodecane ring. The first total synthesis of this demanding target is described, which relies on a highly selective cyclopropanation reaction of an α‐stannylated‐α‐diazoester catalyzed by a heteroleptic dirhodium paddlewheel complex, followed by an unprecedented Stille‐type cross coupling of the resulting stannylated cyclopropane with methyl iodide as the electrophilic partner to form the all‐carbon quaternary stereocenter at one of the bridgehead positions. Equally decisive was the bicyclization strategy based on lactonization/ring expansion that ultimately allowed the strained ten‐membered carbocycle to be forged.

Stille coupling between 5,5′-dibromo-4,4′-diphenyl-2,2′-bithiazole and 9-(2-ethylhexyl)-3-(tributylstannyl)-9H-carbazole in the presence of Pd(Ph3P)2Cl2 in toluene, heated at reflux for 2 h, gave 5,5′-bis[9-(2-ethylhexyl)-9H-carbazol-3-yl]-4,4′-diphenyl-2,2′-bithiazole in 85% yield. [ABSTRACT FROM AUTHOR]

We report a facile synthesis of regioselectively multi‐functionalized pyrenes through one‐pot reactions. These reactions involve Stille and Suzuki coupling reactions, which are proven effective in forming 1,2,3,6,7,8‐hexaphenylethynylpyrene for the first time. The 1,3,6,8‐tetraphenylethynyl pyrenediboronates are essential in synthesizing multi‐functionalized pyrenes, and the results indicate that the Stille coupling reaction is more effective than the Sonogashira coupling reaction in forming these boronate compounds in good yields. Furthermore, the experimental and theoretical investigations into the photophysical and electrochemical properties of the obtained 1,2,3,6,7,8‐multifunctionalized pyrenes show that the phenylethynyl groups at 2,7‐positions further increase the system conjugation, which is significant in developing new materials with enhanced properties. [ABSTRACT FROM AUTHOR]

Bipyridine and related compounds are starting materials or precursors for a variety of valuable substances such as biologically active molecules, ligands for catalysts, photosensitizers, viologens, and supramolecular architectures. Thus, it is important to classify their synthesis methods and understand their characteristics. Representative examples include methods using homo and heterocoupling of pyridine derivatives in the presence of a catalyst. Because bipyridine compounds strongly coordinate with metal centers, a decrease in catalytic activity and yield is often observed in the reaction system. To address this issue, this review provides insights into advances over the last ~30 years in bipyridine synthesis using metal complexes under both homogeneous and heterogeneous conditions. Moreover, strategies for bipyridine synthesis involving sulfur and phosphorous compounds are examined. These alternative pathways offer promising avenues for overcoming the challenges associated with traditional catalysis methods, providing a more comprehensive understanding of the synthesis landscape. [ABSTRACT FROM AUTHOR]

Stille coupling between 5,5′-dibromo-4,4′-diphenyl-2,2′-bithiazole and 9-(2-ethylhexyl)-3-(tributylstannyl)-9H-carbazole in the presence of Pd(Ph3P)2Cl2 in toluene, heated at reflux for 2 h, gave 5,5′-bis[9-(2-ethylhexyl)-9H-carbazol-3-yl]-4,4′-diphenyl-2,2′-bithiazole in 85% yield.

Conjugated polymer semiconductors based on donor–acceptor structures are commonly employed as core materials for optoelectronic devices in the field of organic electronics. In this study, we designed and synthesized a novel acceptor unit thiophene-vinyl-diketopyrrolopyrrole, named TVDPP, based on a four-step organic synthesis procedure. Stille coupling reactions were applied with high yields of polymerization of TVDPP with fluorinated thiophene (FT) monomer. The molecular weight and thermal stability of the polymers were tested and showed high molecular weight and good thermal stability. Theoretical simulation calculations and 2D grazing-incidence wide-angle X-ray scattering (GIWAXS) tests verified the planarity of the material and excellent stacking properties, which are favorable for achieving high carrier mobility. Measurements based on the polymer as an organic thin film transistor (OTFT) device were carried out, and the mobility and on/off current ratio reached 0.383 cm2 V−1 s−1 and 104, respectively, showing its great potential in organic optoelectronics. [ABSTRACT FROM AUTHOR]

Organic polymer semiconductor materials, due to their good chemical modifiability, can be easily tuned by rational molecular structure design to modulate their material properties, which, in turn, affects the device performance. Here, we designed and synthesized a series of materials based on terpolymer structures and applied them to organic thin-film transistor (OTFT) device applications. The four polymers, obtained by polymerization of three monomers relying on the Stille coupling reaction, shared comparable molecular weights, with the main structural difference being the ratio of the thiazole component to the fluorinated thiophene (Tz/FS). The conjugated polymers exhibited similar energy levels and thermal stability; however, their photochemical and crystalline properties were distinctly different, leading to significantly varied mobility behavior. Materials with a Tz/FS ratio of 50:50 showed the highest electron mobility, up to 0.69 cm2 V−1 s−1. Our investigation reveals the fundamental relationship between the structure and properties of materials and provides a basis for the design of semiconductor materials with higher carrier mobility. [ABSTRACT FROM AUTHOR]

Organic polymer semiconductor materials are conveniently tuned to energy levels because of their good chemically modifiable properties, thus enhancing their carrier transport capabilities. Here, we have designed and prepared a polymer with a donor-acceptor structure and tested its potential as a p-type material for organic field-effect transistor (OFET) applications using a solution-processing method. The conjugated polymers, obtained via the polymerization of the two monomers relying on the Stille coupling reaction, possess extremely high molecular weights and thermodynamic stability. Theoretical-based calculations show that PDPP-2S-Se has superior planarity, which is favorable for carrier transport within the main chain. Photophysical and electrochemical measurements systematically investigated the properties of the material and the energy levels with respect to the theoretical values. The maximum hole mobility of the PDPP-2S-Se-based OFET device is 0.59 cm2 V−1 s−1, which makes it a useful material for potential organic electronics applications. [ABSTRACT FROM AUTHOR]

Here we report several useful synthetic strategies to azepino hi‐indoles, that are structural units in natural products by using commercially available indole derivatives such as 7‐bromo indole and 7‐formylindole via palladium catalyzed cross‐coupling reaction, ring closing olefin metathesis (RCM) as key steps. Later, we extended this strategy to seven‐membered fused indoles containing dioxano and dioxocano derivatives via allylation, double bond isomerization and RCM sequence as key step. Additionally, azepino indole having diene moiety was obtained by enyne metathesis and shown to be useful for Diels−Alder strategy. Along similar lines, we also report eight‐membered fused azocino indole using Grignard reaction and RCM as key steps and we demonstrated that the product obtained is useful for Fischer indolization to obtain bis‐indole derivative. Here several synthetically useful transformations were performed to generate diversity in the fused indole derivatives. All the compounds synthesized here are well characterized by NMR and HRMS data.Introduction [ABSTRACT FROM AUTHOR]

The development of n-type organic semiconductor materials for transporting electrons as part of logic circuits is equally important to the development of p-type materials for transporting holes. Currently, progress in research on n-type materials is relatively backward, and the number of polymers with high electron mobility is limited. As the core component of the organic field-effect transistor (OFET), the rational design and judicious selection of the structure of organic semiconductor materials are crucial to enhance the performance of devices. A novel conjugated copolymer with an all-acceptor structure was synthesized based on an effective chemical structure modification and design strategy. PDPPTT-2Tz was obtained by the Stille coupling of the DPPTT monomer with 2Tz-SnMe3, which features high molecular weight and thermal stability. The low-lying lowest unoccupied molecular orbital (LUMO) energy level of the copolymer was attributed to the introduction of electron-deficient bithiazole. DFT calculations revealed that this material is highly planar. The effect of modulation from a donor–acceptor to acceptor–acceptor structure on the improvement of electron mobility was significant, which showed a maximum value of 1.29 cm2 V−1 s−1 and an average value of 0.81 cm2 V−1 s−1 for electron mobility in BGBC-based OFET devices. Our results demonstrate that DPP-based polymers can be used not only as excellent p-type materials but also as promising n-type materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Two new non-fullerene acceptors based on perylene diimide with acetylenic bridges were designed and synthesized employing Stille and Sonogashira coupling reactions as the key steps. Their optical and electronic properties were explored by UV–VIS spectroscopy and cyclic voltammetry, and energies of frontier molecular orbitals were estimated. Their preliminary studies in perovskite solar cells as electron transport materials showed the best power conversion efficiency for photocells of 14.18% value. [ABSTRACT FROM AUTHOR]

This study describes the synthesis of a series of 6-methylphenanthridines and their evaluation as cytotoxic agents. An unprecedented one-pot synthesis involving three steps was established for the preparation of the substituted 6-methylphenanthridines. Eleven 6-methylphenanthridines were tested against human papillomavirus-related endocervical adenocarcinoma (KB 3.1) cells and one compound in this series exhibited cytotoxicity at a submicromolar concentration. The determination of such cytotoxic 6-methylphenanthridine is crucial for further development of a corresponding ring-opened prodrug useful in the "cycl'in-cell" strategy. [Display omitted] • A novel one pot synthesis of 6-methylphenanthridine was developed. • 11 derivatives were tested on KB 3.1 cancer cells in vitro. • A 6-methylphenanthridine displayed submicromolar cytotoxicity against the cancer cell line. [ABSTRACT FROM AUTHOR]

Bipyridine and related compounds are starting materials or precursors for a variety of valuable substances such as biologically active molecules, ligands for catalysts, photosensitizers, viologens, and supramolecular architectures. Thus, it is important to classify their synthesis methods and understand their characteristics. Representative examples include methods using homo and heterocoupling of pyridine derivatives in the presence of a catalyst. Because bipyridine compounds strongly coordinate with metal centers, a decrease in catalytic activity and yield is often observed in the reaction system. To address this issue, this review provides insights into advances over the last ~30 years in bipyridine synthesis using metal complexes under both homogeneous and heterogeneous conditions. Moreover, strategies for bipyridine synthesis involving sulfur and phosphorous compounds are examined. These alternative pathways offer promising avenues for overcoming the challenges associated with traditional catalysis methods, providing a more comprehensive understanding of the synthesis landscape.

Conjugated polymer semiconductors based on donor–acceptor structures are commonly employed as core materials for optoelectronic devices in the field of organic electronics. In this study, we designed and synthesized a novel acceptor unit thiophene-vinyl-diketopyrrolopyrrole, named TVDPP, based on a four-step organic synthesis procedure. Stille coupling reactions were applied with high yields of polymerization of TVDPP with fluorinated thiophene (FT) monomer. The molecular weight and thermal stability of the polymers were tested and showed high molecular weight and good thermal stability. Theoretical simulation calculations and 2D grazing-incidence wide-angle X-ray scattering (GIWAXS) tests verified the planarity of the material and excellent stacking properties, which are favorable for achieving high carrier mobility. Measurements based on the polymer as an organic thin film transistor (OTFT) device were carried out, and the mobility and on/off current ratio reached 0.383 cm2 V−1 s−1 and 104, respectively, showing its great potential in organic optoelectronics.

Organic polymer semiconductor materials are conveniently tuned to energy levels because of their good chemically modifiable properties, thus enhancing their carrier transport capabilities. Here, we have designed and prepared a polymer with a donor-acceptor structure and tested its potential as a p-type material for organic field-effect transistor (OFET) applications using a solution-processing method. The conjugated polymers, obtained via the polymerization of the two monomers relying on the Stille coupling reaction, possess extremely high molecular weights and thermodynamic stability. Theoretical-based calculations show that PDPP-2S-Se has superior planarity, which is favorable for carrier transport within the main chain. Photophysical and electrochemical measurements systematically investigated the properties of the material and the energy levels with respect to the theoretical values. The maximum hole mobility of the PDPP-2S-Se-based OFET device is 0.59 cm2 V−1 s−1, which makes it a useful material for potential organic electronics applications.

Organic polymer semiconductor materials, due to their good chemical modifiability, can be easily tuned by rational molecular structure design to modulate their material properties, which, in turn, affects the device performance. Here, we designed and synthesized a series of materials based on terpolymer structures and applied them to organic thin-film transistor (OTFT) device applications. The four polymers, obtained by polymerization of three monomers relying on the Stille coupling reaction, shared comparable molecular weights, with the main structural difference being the ratio of the thiazole component to the fluorinated thiophene (Tz/FS). The conjugated polymers exhibited similar energy levels and thermal stability; however, their photochemical and crystalline properties were distinctly different, leading to significantly varied mobility behavior. Materials with a Tz/FS ratio of 50:50 showed the highest electron mobility, up to 0.69 cm2 V−1 s−1. Our investigation reveals the fundamental relationship between the structure and properties of materials and provides a basis for the design of semiconductor materials with higher carrier mobility.

The development of n-type organic semiconductor materials for transporting electrons as part of logic circuits is equally important to the development of p-type materials for transporting holes. Currently, progress in research on n-type materials is relatively backward, and the number of polymers with high electron mobility is limited. As the core component of the organic field-effect transistor (OFET), the rational design and judicious selection of the structure of organic semiconductor materials are crucial to enhance the performance of devices. A novel conjugated copolymer with an all-acceptor structure was synthesized based on an effective chemical structure modification and design strategy. PDPPTT-2Tz was obtained by the Stille coupling of the DPPTT monomer with 2Tz-SnMe3, which features high molecular weight and thermal stability. The low-lying lowest unoccupied molecular orbital (LUMO) energy level of the copolymer was attributed to the introduction of electron-deficient bithiazole. DFT calculations revealed that this material is highly planar. The effect of modulation from a donor–acceptor to acceptor–acceptor structure on the improvement of electron mobility was significant, which showed a maximum value of 1.29 cm2 V−1 s−1 and an average value of 0.81 cm2 V−1 s−1 for electron mobility in BGBC-based OFET devices. Our results demonstrate that DPP-based polymers can be used not only as excellent p-type materials but also as promising n-type materials.

The polyenoyltetramic acids pyranonigrin J (3) and pyranonigrin I (4) had been isolated from Aspergillus niger. Their origins from and roles in biosynthesis as well as the S‐configurations of their stereocenter had been deduced from expression experiments with modifications of the corresponding gene cluster. We corroborated this stereochemical assignment after executing the first total syntheses of both compounds because they had essentially the same specific rotations as their natural counterparts. Our syntheses used the β‐ketothioester 18 as a conjunctive reagent. It was combined with the l‐serine derivatives (S)‐19 or (S)‐21 ("Western building blocks"), respectively, through aminolyses. Stille couplings with the stannane 13 ("Eastern building block") followed. The resulting β‐ketoamides (S)‐11 and (S)‐12 underwent desilylative Lacey‐Dieckmann cyclizations when exposed to 8 equiv. of Bu4NF. They rendered the polyenoyltetramic acids (S)‐26 [acidolysis: → (S)‐3] and (S)‐4, respectively. [ABSTRACT FROM AUTHOR]

The inthomycin family of antibiotics, isolated from Streptomyces strains, are interesting molecules for synthesis due to their characteristic common oxazole polyene chiral allylic β-hydroxycarbonyl fragments and significant biological activities. The full structural motif of the inthomycins is found in several more complex natural products including the oxazolomycins, 16-methyloxazolomycin, curromycins A and B, and KSM-2690. This review summarises the application of various efforts towards the synthesis of inthomycins and their analogues systematically.

Stille coupling is regarded as a powerful tool in the synthesis of a wide range of functionalised C–C bonds due to the high stability, availability and broad functional group compatibility of the organostannanes. This is the first review solely focused on the role of the non‐palladium transition metals in Stille coupling with emphasis on their catalytic capacity and mechanistic details. Several transition metals including Mn, Ni, Cu, Rh, Pt, and Au are found highly efficient in the coupling with Cu having the largest reports. Importantly, Cu‐catalysed Stille couplings formed the key stages in the synthesis of therapeutic molecules like 4(S)‐11‐diHDHA and Spliceostatin derivatives. Greener protocols including reusable heterogeneous catalytic systems are promising alternatives and some have even shown dominance over Pd catalysts. This review comprises all available literature on non‐palladium Stille coupling up to June 2021. [ABSTRACT FROM AUTHOR]

Isoflavones were synthesized from the reaction of 3‐bromochromone derivatives and aryltributylstannanes via Stille coupling catalyzed by a water‐soluble and reusable PdCl2(NH3)2/2,2′‐cationic bipyridyl system in aqueous solution. For prototype 3‐bromochromone, the coupling reaction was performed at 80°C for 24 hr with 2.5 mol% catalyst in water in the presence of tetrabutylammonium fluoride. After the reaction, the aqueous solution could be reused for several runs, indicating that its activity was only slightly decreased. For substituted 3‐bromochromones, the addition of NaHCO3 and a higher reaction temperature (120°C) were required to gain satisfactory outcomes. In addition, naturally occurring products, such as daidzein, could be obtained by this protocol via a one‐pot reaction. [ABSTRACT FROM AUTHOR]

Abstract Pyrido-oxazine derivatives have been synthesized by employing tandem SN2 and SNAr reaction between 2,4,6-tribromo-3-(2-bromoethoxy)pyridine or 2,4,6-tribromo-3-(3-bromopropoxy)pyridine and a variety of primary amines. Moderate to good regioselectivity in favor of cyclization at the 2-position is observed. Pyrido-oxazine products thus generated are converted into biarylated pyrido-oxazine and terpyridine ligands.

We report herein the synthesis of siloxane-functionalized CBP molecules (4,4′-bis(carbazole)-1,1′-biphenyl) for liquid optoelectronic applications. The room-temperature liquid state is obtained through a convenient functionalization of the molecules with heptamethyltrisiloxane chains via hydrosilylation of alkenyl spacers. The synthesis comprises screening of metal-catalyzed methodologies to introduce alkenyl linkers into carbazoles (Stille and Suzuki Miyaura cross-couplings), incorporate the alkenylcarbazoles to dihalobiphenyls (Ullmann coupling), and finally introduce the siloxane chains. The used conditions allowed the synthesis of the target compounds, despite the high reactivity of the alkenyl moieties bound to π-conjugated systems toward undesired side reactions such as polymerization, isomerization, and hydrogenation. The features of these solvent-free liquid CBP derivatives make them potentially interesting for fluidic optoelectronic applications.

Divergent enantioselective total syntheses of five naturally occurring post‐iboga indole alkaloids, dippinine B and C, 10,11‐demethoxychippiine, 3‐O‐methyl‐10,11‐demethoxychippiine, and 3‐hydroxy‐3,4‐secocoronaridine, as well as the two analogues 11‐demethoxydippinine A and D, are presented for the first time. The enantioenriched aza[3.3.1]‐bridged cycle, a common core intermediate to the target molecules, was constructed through an asymmetric phase‐transfer‐catalyzed Michael/aldol cascade reaction. The challenging azepane ring fused around the indole ring and the [3.3.1]‐bridged cycle were installed through an intramolecular SN2′‐type reaction. These cyclization strategies enabled rapid construction of the [6.5.6.6.7]‐pentacyclic core at an early stage. Highlights of the late‐stage synthetic steps include a Pd‐catalyzed Stille coupling and a highly stereoselective catalyst‐controlled hydrogenation to incorporate the side chain at C20 with both R and S configurations in the natural products. [ABSTRACT FROM AUTHOR]

The heteroleptic dirhodium paddlewheel catalyst 7 with a chiral carboxylate/acetamidate ligand sphere is uniquely effective in asymmetric [2+1] cycloadditions with α‐diazo‐α‐trimethylstannyl (silyl, germyl) acetate. Originally discovered as a trace impurity in a sample of the homoleptic parent complex [Rh2((R)‐TPCP)4] (5), it is shown that the protic acetamidate ligand is quintessential for rendering 7 highly enantioselective. The ‐NH group is thought to lock the ensuing metal carbene in place via interligand hydrogen bonding. The resulting stannylated cyclopropanes undergo "stereoretentive" cross coupling, which shows for the first time that even chiral quarternary carbon centers can be made by the Stille–Migita reaction. [ABSTRACT FROM AUTHOR]

A variety of 1,3-disubstituted naphthalenes have been prepared by palladium-catalyzed annulation of (o -ethynylphenyl)acetyl chloride with design of a new synthetic strategy by Stille coupling using functionalized organostannanes. The method affords excellent yields of the substituted naphthalenes and accommodates a wide variety of functional groups under mild conditions. Mechanistic studies show intramolecular cyclization as a major step following C–C bond coupling. [ABSTRACT FROM AUTHOR]

Stille coupling of 3,5-bis(5-bromothien-2-yl)-4H-1,2,6-thiadiazin-4-one (10) with 2-(tri-n-butylstannyl)thiazole and Pd(Ph3P)2Cl2 in PhMe, at ca. 110 °C, for 2 h, gave 3,5-bis[5-(thiazol-2-yl)thien-2-yl]-4H-1,2,6-thiadiazin-4-one (9) in 81% yield. The latter is evaluated for its electronic properties.

This work is described; Pd–cytosine complex immobilized on functionalized hexagonal mesoporous silica for synthesis of novel mesoporous catalyst (HMS–CPTMS–Cy–Pd). Also the catalytic activity of this new catalyst was investigated for Stille and Suzuki coupling reactions. In this paper, Pd–cytosine complex immobilized on functionalized hexagonal mesoporous silica (HMS–CPTMS–Cy–Pd) as a novel mesoporous catalyst with high activity for the Stille and Suzuki coupling reactions was successfully fabricated. All products were obtained in good to excellent yields at low time reaction. The prepared catalyst has been characterized using various techniques such as FT-IR, XRD, BET, SEM, EDX-MAP, TGA and ICP. Recovery test confirm that the synthesized catalyst can be able to reuse for several times. [ABSTRACT FROM AUTHOR]

An array of semiconducting oligoselenophenes (n and p types), up to hexamer units, has been synthesized by the double Stille coupling methods using tetrakis(triphenylphosphine)palladium(0) as a catalyst. A series of semiconducting oligomers (n and p types) containing mixed hetero-units (hexamers of thiophene and selenophene) have been also synthesized using the Stille coupling reaction. Their thermal properties are systematically studied and compared with those of π-conjugated thiophene based oligomers using DSC and TGA. The field-effect mobility of synthesized n and p type oligomers is analyzed. [ABSTRACT FROM AUTHOR]

An efficient bioinspired stereoselective first total synthesis of spinosulfate B has been accomplished following Jacobsen's hydrolytic kinetic resolution, Stille coupling, olefin‐cross metathesis (OCM), Horner Wadsworth Emmons olefination, and De Brabander's esterification as key steps. [ABSTRACT FROM AUTHOR]

Gold nanoparticle catalysts are important in many industrial production processes. Nevertheless, for traditional Csp2 −Csp2 cross‐coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form Csp3 −Csp3 bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, which allowed for convenient catalyst recovery and reuse. The present study is a rare case where a gold metal catalyst is superior to Pd catalysts in a cross‐coupling reaction of an organic halide and an organometallic reagent. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Efficient synthesis of novel benzoylbenzamide derivatives of 17α-vinyl estradiols. • All compounds demonstrate high relative binding affinity (1–9%) at both estrogen receptor subtypes. • The meta-substituted compound 6 h demonstrates high affinity and full efficacy. • Molecular modeling studies of isomers suggest a novel binding mode for 6 h. • Results suggest approach to new 17α-substituted estradiol derivatives as molecular probes. Abstract A series consisting of substituted benzoylbenzamide derivatives of 17α-E-vinyl estradiol 6a-i and 7a-d was prepared in good overall yields from the corresponding novel iodinated benzoylbenzamide precursors using Pd(0)-catalyzed Stille coupling. Biological evaluation using competitive binding assays indicated that all compounds were effective ligands for the ERα- and ERβ-LBD (RBA = 0.5–10.0% of estradiol). Most of the compounds expressed lower stimulatory (agonist) potency (RSA <0.2–0.5%) compared to their binding affinity, however, the meta-substituted isomer 6h demonstrated a level of efficacy (RSA = 5.7%) comparable to its affinity (RBA = 9.5%). Docking studies of 6b , 6h , and 6i with the 2YAT crystal structure suggested that higher affinity and efficacy of 6h are due to an effective set of interactions with exposed receptor sidechains not observed with the ortho- and para- isomers. In this binding model, the terminal ring of the ligand is exposed to the solvent space, which would explain both the small variation in RBA values and the narrow SAR for the diverse structural features. [ABSTRACT FROM AUTHOR]

Abstract Herein we describe the detail on our full investigations that led to the achievement of the total synthesis of nannocystin Ax, a 21-membered macrocyclic natural product composing of a tripeptide fragment and a polyketide fragment, which featured in 8 longest linear steps in with 13.9% total overall yield. The key synthetic strategy relied on the late-stage stille coupling for the macrolactonization to construct the 21-membered ring, while direct connection between the tripeptide fragment and the polyketide fragment failed. 1H NMR experiments reveal that nannocystin Ax should exist as conformational mixtures in deuterated solvents. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

A new synthesis of pyrazolo[4,3-d]pyrimidines and isoxazolo[4,5-d]pyrimidines is described. Key steps in the synthesis involve Stille coupling of 4,6-dichloro-2-phenyl-pyrimidine with tributyl(1-ethoxyvinyl)stannane and tandem Schiff-base formation/heterocyclization of 2,6-di-aryl-5-fluoro-4-acetylpyrimidine with hydrazines or -hydroxylamine to give pyrazolo[4,3-d]pyrimidines and isoxazolo[4,5-d]pyrimidines, respectively. The position of the fluoro group in the -pyrimidine ring is important for the success of heterocylization reaction. [ABSTRACT FROM AUTHOR]

The C1–C17 segment of bafilomycin N has been synthesized. The C1–C11 segment was synthesized by the anti -selective vinylogous Mukaiyama aldol reaction with a chiral vinylketene silyl N , O -acetal and the Horner–Wadsworth–Emmons reaction, whereas C12–C17 was constructed by the syn -selective vinylogous Mukaiyama aldol reaction and the Jung's semipinacol rearrangement. Those segments were connected by the Stille coupling to afford the C1–C17 segment. [ABSTRACT FROM AUTHOR]

The bis‐guanidinium toxins are a collection of natural products that display nanomolar potency against select isoforms of eukaryotic voltage‐gated Na+ ion channels. We describe a synthetic strategy that enables access to four of these poisons, namely 11‐saxitoxinethanoic acid, C13‐acetoxy saxitoxin, decarbamoyl saxitoxin, and saxitoxin. Highlights of this work include an unusual Mislow–Evans rearrangement and a late‐stage Stille ketene acetal coupling. The IC50 value of 11‐saxitoxinethanoic acid was measured against rat NaV1.4, and found to be 17.0 nm, similar to those of the sulfated toxins gonyautoxin II and III. [2,3]=4 toxins: A synthetic strategy that enables access to four naturally occurring guanidinium toxins, namely saxitoxin, decarbamoyl saxitoxin, C13‐acetoxy saxitoxin, and C11‐saxitoxinethanoic acid, is detailed. Highlights of this work include an unusual Mislow–Evans rearrangement and a late‐stage Stille ketene acetal cross‐coupling reaction. [ABSTRACT FROM AUTHOR]

α-Conjugated oligoselenophenes are characterized by very low solubility in organic solvents. Their higher solubility may be achieved by introducing alkyl side chains into the β-positions of selenophene moieties. For the first time, β,β′-dihexyl sexiselenophene is synthesized according to the conventional approach. Physical and electrochemical studies of β,β′-dialkyl oligomers are analyzed and compared with corresponding thienyl oligomers. [ABSTRACT FROM AUTHOR]

An alternative catalytic strategy for the preparation of benzylmethacrylate esters, key intermediates in the synthesis of coenzyme Q10 and derivatives, was reported. This strategy avoided undesirable stoichiometric reduction/oxidation processes by utilizing the catalytic formation of allylarenes and then cross-metathesis to selectively form E-benzylmethacrylate esters with good yields (58−64%) and complete E-selectivity. The ester intermediates were reduced to common key benzylallylic alcohols (90−92% yield), which were subsequently used in the formal syntheses of coenzyme Q10 and one derivative.

Abstract: The marine macrolide chagosensine is the only natural product known to date that embodies a Z,Z‐configured chloro‐1,3‐diene unit. This distinguishing substructure was prepared by a sequence of palladium‐catalyzed 1,2‐distannation of an alkyne precursor, regioselective Stille cross‐coupling at the terminus of the resulting bisstannyl alkene with an elaborated alkenyl iodide, followed by chloro‐destannation of the remaining internal site. The preparation of the required substrates centered on cobalt‐catalyzed oxidative cyclization reactions of hydroxylated olefin precursors, which allowed the 2,5‐trans‐disubstituted tetrahydrofuran rings, embedded into each building block, to be formed with excellent selectivity. The highly strained macrolactone could ultimately be closed under forcing Yamaguchi conditions. Comparison of the spectral data of the synthetic sample with those of authentic chagosensine methyl ester confirmed that the structure of this intriguing compound has been mis‐assigned by the isolation team. [ABSTRACT FROM AUTHOR]

Abstract: Nonstoichiometric polycondensations via Stille coupling reactions are successfully used to obtain high‐molecular‐weight π‐conjugated polymers using 2,5‐bis(trimethylstannyl)thiophene and a dibromo phthalimide monomer, N‐hexyldecyl‐3,6‐dibromophthalimide (2), in excess from 1:1 to 1:10. The intramolecular Pd(0) catalyst transfer on 2 substituted at the polymer terminal occurs as suggested by the model reaction between 2‐(tributylstannyl)thiophene and an equimolar amount of N‐octyl‐3,6‐dibromophthalimide (4), and the reaction generates only the disubstituted compound and excess 4 in an almost 1:1 ratio. The effect of the structures of the ligands and monomers on the polymerization under nonstoichiometric conditions is investigated to elucidate the criteria for the successful intramolecular catalyst transfer. The combination of the imide structure and an electron‐rich ligand is important for promoting the catalyst transfer. [ABSTRACT FROM AUTHOR]

Novel analogues of the plant hormone abscisic acid (ABA) were designed and prepared to explore the impact that modifications of its terpenoid side chain have on receptor affinity and in vivo efficacy against drought stress in selected crops. Their efficient and versatile synthesis proceeded via Stille or Sonogashira couplings, shortening the synthetic route significantly. In line with molecular modelling and X-ray crystallography studies novel ABA-derivatives with small alkyl, cycloalkyl or haloalkyl substituents showed strong effects in vitro and in vivo against drought stress in crops, particularly canola and wheat. [ABSTRACT FROM AUTHOR]

Synthetic analogues of plant hormone abscisic acid (ABA) bearing a yet unexplored head group motif were prepared based on a combination of agrochemical experience, in vivo hits and structure-based design. It could thus be explored how modifying key parts of ABA's cyclohexenone unit influenced receptor affinity and in vivo efficacy against drought stress in selected crops. Cyano-cyclopropyl groups proved to be suitable replacements of the cyclohexanone moiety leading to ABA analogues with strong activity in vitro and in vivo. Their efficient and versatile synthesis proceeded via Stille or Sonogashira couplings as the key steps. Combining novel cyano-cyclopropyl headgroups with previously identified substituents in the terpenoid side chain afforded the most promising effects against drought stress in crops, particularly canola and wheat. [ABSTRACT FROM AUTHOR]

A scalable 5-step synthesis of the diazacarbazole derivative 1 used as tau PET tracer precursor is reported. Key features of this synthesis include a Buchwald-Hartwig amination, a Pd catalyzed C H activation and a Suzuki-Miyaura cross-coupling. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, Pd–4,6-diamino-2-pyrimidinethiol complex supported on SBA-15 as a novel heterogeneous catalyst with high activity for the reaction of aryl halides with phenylboronic acid or triphenyltin chloride have been well explored. The prepared catalyst has been characterized by Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, N2 adsorption/desorption isotherms (BET), transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis and inductively coupled plasma analysis. The synthesized nanocatalyst could be easily recovered from the reaction mixture and reused five times without any loss in activity.Graphical Abstract: [ABSTRACT FROM AUTHOR]

[Display omitted] • Highly electron-deficient and less sterically-hindered phosphine ligands. • Least steric hindrance to a metal center among triarylphosphine ligands. • Effective phosphine ligands for the Stille coupling of aryl iodides. • π–π Stacking interactions between two ligand moieties in the palladium complex. Highly electron-deficient and less sterically-hindered phosphine ligands with two or three 1,3,5-triazinyl groups on the phosphorus atoms have been synthesized and examined in transition metal-catalyzed reactions for the first time. Due to the lack of any hydrogens or substituents at ortho -positions of the 1,3,5-triazine towards the phosphorous atom, it is considered that the steric hindrance of the tris(triazinyl)phosphine ligand to a metal center is least among triarylphosphine ligands. In the Stille coupling of aryl iodides, these electron-poor phosphine ligands provided good product yields compared to hitherto well-known phosphine ligands. [ABSTRACT FROM AUTHOR]