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A silver-catalyzed, K2S2O8-mediated protocol to access regioselective acylarylation of unactivated alkenes was developed. The reaction between N-allyl-indoles and α-oxocarboxylic acids proceeded smoothly and involved an acyl radical addition/C–H cyclization cascade. The protocol showed a broad substrate scope and good tolerance of functional groups. The reaction proceeded with both internal and terminal alkenes to furnish many functional pyrrolo[1,2-a]indoles bearing the ketone carbonyl group, and this feature also provides the potential to construct structurally complex N-containing heterocycles.

Treatment of alkynes with diethyl phosphite and t-butyl hydroperoxide in the presence of [Cu(MeCN)4]BF4 under microwave irradiation produced the oxyphosphorylation of the triple bond, giving rise to the corresponding s-ketophosphonates in moderate-to-good yields. When the triple bond was conjugated to a carbonyl group bearing an aromatic ring, it led to the cyclization of the resulting ketone intermediate, producing eventually different phosphonylated indenones.

DFT study was employed to gain insight into methylene oxidation catalyzed by Mn(CF3-PDP)(NCMe)2 (SbF6)2/H2O2/HOAcCl(OACCl ═OC(O)CH2Cl). The active catalyst was characterized to be [Mn](O)OAcCl ([Mn]═Mn(CF3-PDP)2+) which is generated via a sequence from [Mn] to [Mn]OH to [Mn]OAcCl to [Mn]OOH. With the active catalyst, the methylene group is sequentially oxidized to an alcohol and then to a carbonyl group via rebound mechanism. The mechanism explains the observed site selectivity.

A hetero-tetranuclear CeNi3 complex with a macrocyclic ligand catalysed the aerobic oxygenation of a methylene group adjacent to a carbonyl group under visible-light radiation to produce the corresponding α-diketones. The visible-light induced homolysis of the Ce–O bond of a bis(enolate) intermediate is proposed prior to aerobic oxygenation.

We describe a novel mechanism of stabilization of the E-ac isomer of an arylhydrazide via nN → π*Ar interactions. We further show that when a leaving group (F) is present at the ortho-position of the carbonyl group of such an arylhydrazide, the nN → π*Ar interaction facilitates an SNAr autocyclization reaction to produce indazolone, an important heterocycle with biological activity. Faster autocyclization of arylhydrazide is observed when an electron withdrawing group is present in the aryl ring, which is a characteristic of SNAr reactions.

Umpolung is a unique strategy which converts the property of an atom into the opposite one. An efficient and general method for the construction of quinoline N-oxides via umpolung of carbonyl group...

Bis(2-pyridylcarbonyl)aminate (bpca) coordinates to a ruthenium center with three nitrogen atoms of two pyridyl and one aminate group and the biscarbonylaminate moiety ({O-C-N-C-O}−) functions as a...

Some derivatives of 1-carbamoylhydantoins undergo cleavage at the N1–C(O) bond on heating in solution. 1-Carbamoylhydantoins in aqueous and alcoholic ammonia rearrange via opening of the imidazole ring, followed by recyclization. Prolonged treatment of 1-carbamoylhydantoins with aqueous ammonia can lead to elimination of the C2=O carbonyl group.

A newly devised radical-based strategy enabled coupling between multiply oxygenated α-alkoxyacyl tellurides and 2-hydroxybenzaldehyde derivatives. A reagent combination of Et3 B, Et2 AlCl, and O2 promoted the formation of the α-alkoxy carbon radical from the α-alkoxyacyl telluride and the addition of the radical to the carbonyl group of 2-hydroxybenzaldehyde. The reaction chemo- and stereoselectively forged the hindered C-C bond between two oxygen-functionalized carbons at ambient temperature. The method was applied to the preparation of 12 coupling adducts with three to six contiguous stereocenters and to the concise synthesis of an antitumor compound, LLY-283.

Reaction of 2,2′,2″-(2,4,6-trioxo-1,3,5-triazinane-1,3,5-triyl)triacetic acid derivatives with nucleophiles in aqueous medium involved opening of the triazinane ring with elimination of carbonyl group, followed by recyclization to 1-carbamoylhydantoins.

Some geometrical isomers of tetranitro-tetraazabicyclonanones (the titled compounds) and some of their constitutional isomers are investigated quantum chemically at the level of B3LYP/6-311++G(d,p). The constitutional isomers differ from the title compounds by the position of the carbonyl group. All the structures are nitramines (actually nitramides of organic sense). The constitutional isomers considered are capable of exhibiting proton tautomerism (keto-enol type). The tautomers have also been subjected to density functional treatment at the same level of calculation. For all the structures various electronic, energetic and spectral data have been collected and discussed.

Herein we have disclosed a Zn(OTf)2 catalyzed synthesis of C2-alkyl substituted indole derivatives via unprecedented carbonyl group migration from o-amido alkynols. The key features of this protoco...

A new synthetic route has been developed for the construction of the main skeleton of ω-aryloxyprostaglandin (PG) via 1,2-addition of lithiated 3-methyl-3-(trimethylsilyloxy)pent-1-yne to the ketone carbonyl group of ethyl 7-(5-oxocyclopent-1-en-1-yl)heptanoate. The addition reaction was accompanied by the formation of cyclopentenone dimer as minor product. The 1,2-adduct containing a tertiary hydroxy group was oxidized with pyridinium chlorochromate to 13-dehydro-PGB1 ethyl ester.

Addition of ethanol and diethyl phosphonate to the carbonyl group of 2,2-dichloro-2-(diethoxyphosphoryl)-acetaldehyde has been studied, and the corresponding α-chloro ether, acetal, and phosphorylated metrifonate have been obtained. α,α-Dichloro-α-phosphoryl carbonyl compounds have been found to undergo haloform cleavage by the action of bases. Perkow reaction of mono- and dichloro(diethoxyphosphoryl)acetaldehydes with triethyl phosphite afforded diethyl 2-(diethoxyphosphoryl)ethenyl phosphates.

The synthesis of 3-fluoro-2,5-disubstituted furans from gem-difluorocyclopropyl ketones was accomplished using trifluoromethanesulfonic acid (CF3SO3H) through ring expansion owing to the activation of the carbonyl group in the starting material. The present synthesis of 3-fluorofurans tolerates substrates designed for products with aromatic substituents at the C-2 and C-5 positions.

Direct carbonylation of the C-H bond is a great tool for installing a carbonyl group in a wide variety of substrates. This review summarizes the C-H bond carbonylation methodologies using the cobalt-catalyzed C-H bond functionalization approach. Despite the fact that cobalt-catalyzed carbonylation methodologies have been known since Murahashi's report in 1955, this area is still underdeveloped, particularly carbonylation of the C(sp3)-H bond.

An efficient enantioselective [3+2] cycloaddition of isomunchnones with methyleneindolinones that are generated by an in situ intramolecular addition of the carbonyl group to rhodium carbenes is realized with a chiral N,N′-dioxide/Zn(II) complex as a Lewis acid. A series of chiral oxa-bridged 3-spiropiperidines are obtained in high yields with excellent dr and excellent ee values.

Keto–enol tautomerization of carbonyl compounds to their enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of enol followed by an H insertion into the enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–enol dimers, in which the normally unstable form of enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–enol dimers can attach an H atom to form a reaction inter...

The activated alkynes have been used successfully for the first time as the dipolarophile in the palladium-catalyzed asymmetric (3 + 2) cycloaddition, affording highly functionalized cyclopentenes in good to high yields with high chemoselectivities and good to high enantioselectivities. The introduction of an additional carbonyl group at the α-position of the alkynyl esters is the key to activating the carbon-carbon triple bond. The reaction process was investigated, and an inverse process of Pd-catalyzed (3 + 2) cycloaddition was observed.

Synthesis of 4-acetyl-substituted azoles (1,2,3-triazole, 1,2,3-thiadiazole, and 1,2-oxazole) is reported. Organocatalytic reactions of 4-acetyl-1,2,3-triazoles with aryl azides were used to obtain bis-1,2,3-triazoles containing directly linked ring systems. The reactions of 4-acetylazoles with DMF–DMA led to the formation of enamines. It was found that the acetyl and methyl groups in 4-acetyl-5-methyl-1,2,3-thiadiazole competed for the role of reactive site. The obtained enamines reacted with aryl azides, forming bisheterocycles that were linked by a carbonyl group. The structures of the synthesized compounds were proved by NMR spectroscopy, mass spectrometry, and X-ray structural analysis.

Completely substituted p-nitrosophenols were synthesized by cyclocondensation of dimethyl 3-oxopentanedioate with 2-(hydroxyimino)-1-pyridylbutane-1,3-diones. The yield of the final product depended on the position of the nitrogen atom in the pyridyl substituent and was considerably lower for the pyridin-2-yl derivative. According to the DFT B3LYP-D3/6-311G(d,p) quantum chemical calculations, the reason for the reduced reactivity of the carbonyl group linked to C2 of the pyridine ring is their nearly coplanar arrangement. Pyridin-3-yl and pyridin-4-yl substituents are located at a larger angle with respect to the carbonyl group, so that the reactivity of the latter increases.

1,3-Azaprotio transfer of propargylic α-ketocarboxylate oximes, a new type of alkynyl oximes featuring an ester tether, has been explored by taking advantage of gold catalysis. The incorporation of an oxygen atom to the chain of alkynyl oximes led to the formation of two different oxa-cyclic nitrones. It was found that internal alkynyl oximes with an E-configuration deliver five-membered nitrones, whereas terminal alkynyl oximes with an E-configuration afford six-membered nitrones. DFT calculations on four possible pathways supported a stepwise formation of C-N and C-H bonds, in which a 1,3-acyloxy-migration competes with the 1,3-azaprotio-transfer, especially in the case of internal alkynyl oximes. The relative nucleophilic properties of oxygen in the carbonyl group and the nitrogen in the oxime, the electronic effects of alkynes, and the influence of the ring system have been investigated computationally.

Reactions involving Rh(II)-azavinylcarbenes (Rh(II)-AVCs) to synthesize nitrogen-containing compounds have attracted significant research interest. Despite the importance of these reactions, controlling the chemoselectivities in the reactions involving Rh(II)-AVC remains a challenge. To understand the mechanisms and factors controlling the chemoselectivities between N-H and C═O groups of carbamates and amides in reactions involving Rh(II)-AVC, computational studies were employed. The results reveal that not only the greater nucleophilicity of the N-H group than that of the carbonyl group, but also the presence of H-bonding interactions, could favor the addition of the N-H group of primary carbamates to Rh(II)-AVC. However, for secondary carbamates and amides, they could undergo either chemoselective N-H or C═O addition. Secondary carbamates with less steric hindrance, such as oxazolidinone, prefer the N-H addition mode. However, a switch in chemoselectivity (preference for the C═O addition) was revealed for the sterically hindered secondary carbamates/amides. In addition, a possible O-H addition pathway via the keto-enol tautomerization for isatin and isatoic anhydride was disregarded due to the energetically demanding barrier. Instead, a pathway involving the chemoselective C═O addition, formal [3 + 2] cycloaddition, followed by ring opening was proposed. The origins of the chemoselectivity and the factors responsible were addressed.

WOS: 000465322800001, PubMed: 31164929, In this study, we developed a new addition reaction of chlorosulfonyl isocyanate (CSI), starting from 2-ethyl-3a, 4,7,7a-tetrahydro-1H- isoindole-1,3(2H)-dione. The addition reaction of CSI with 2-ethyl-3a, 4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione resulted in the formation of ylidenesulfamoyl chloride, whose exact configuration was determined by X-ray crystal analysis. We explain the mechanism of product formation supported by theoretical calculations., Department of Chemistry; Ataturk University; Scientific and Technological Research Council of Turkey [TUBITAK-116Z506], The authors are indebted to Department of Chemistry and Ataturk University for financial support. This research was supported by the Scientific and Technological Research Council of Turkey (TUBITAK-116Z506).

The addition of 1 equiv of KO(2) and Kryptofix222 (Krypt) in CH(3)CN to a solution of LCu(CH(3)CN) [L = N,N′-bis(2,6-diisopropylphenyl)-2,6-pyridinecarboxamide] in tetrahydrofuran at −80 °C yielded [K(Krypt)][LCuO(2)], the enhanced stability of which enabled reexamination of its reactivity with 2-phenylpropionaldehyde (2-PPA). Mechanistic and product analysis studies revealed that [K(Krypt)][LCuO(2)] reacts with wet 2-PPA to form [LCuOH](−), which then, deprotonates 2-PPA to yield the copper(II) enolate complex [LCu(OC=C(Me)Ph)](−). Acetophenone was observed upon workup of this complex or mixtures of KO(2) and 2-PPA alone, in support of an alternative mechanism(s) to the one proposed previously involving an initial nucleophilic attack at the carbonyl group of 2-PPA.

The significance of gold–carbonyl group interactions in the electrochemistry of anthraquinone thiol derivatives disclosed via specific proximity to gold surfaces., New anthraquinone derivatives with either a single or two thiol groups (AQ1 and AQ2) were synthesized and immobilized in self-assembled monolayers (SAMs) on Au(111) electrodes via Au–S bonds. The resultant AQ1- and AQ2-SAMs were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which enabled mapping of the gold–carbonyl group interactions and other dynamics in the Au–S bound molecular framework. Understanding of these interactions is important for research on thiol-coated gold nanoclusters, since (I) anthraquinone derivatives are a major compound family for providing desired redox functionality in multifarious assays or devices, and (II) the gold–carbonyl interactions can strongly affect anthraquinone electrochemistry. Based on equivalent circuit analysis, it was found that there is a significant rise in polarization resistance (related to SAM structural reorganization) at potentials that can be attributed to the quinone/semi-quinone interconversion. The equivalent circuit model was validated by calculation of pseudocapacitance for quinone-to-hydroquinone interconversion, in good agreement with the values derived from CV. The EIS and CV patterns obtained provide consistent evidence for two different ECEC (i.e. proton-controlled ET steps, PCET) pathways in AQ1- and AQ2-SAMs. Notably, it was found that the formal reorganization (free) energies obtained for the elementary PCET steps are unexpectedly small for both SAMs studied. This anomaly suggests high layer rigidity and recumbent molecular orientation on gold surfaces, especially for the AQ2-SAMs. The results strongly indicate that gold–carbonyl group interactions can be controlled by favorable structural organization of anthraquinone-based molecules on gold surfaces.

A variety of ketonitrones were synthesized in moderate to excellent yields with high chemo-, regio-, and stereoselectivity by using carbonyl-directed addition of N-alkylhydroxylamines to unactivated alkynes under mild conditions. The product diverisity could be controlled by the use of different bases, and EtN( n-Pr)2 could promote the formation of ketonitrones while using EtONa as base led to indanone-derived nitrones. Control experiments indicated that the carbonyl group of the substrate acted as an H-bond acceptor except for an electron-withdrawing group, and conjugated enone skeleton accounted for the high selectivity.

The reactions of Ru3(CO)12 with alkynyl ketones R1CCC(O)R2 (R1 = Et, R2 = Me (1); R1 = Ph, R2 = Me (2); R1 = n-hexyl, R2 = Ph (3); R1 = H, R2 = CH3 (4); and R1 = C(O)OCH3, R2 = OCH3 (5)) proceeds in toluene with the formation of three ruthenoles (1a–3a), four CO-inserted binuclear clusters (1b–2b, 1c and 3c), a tetranuclear cluster 4a, a binuclear cluster 5a and a cyclotrimerization product 5b. Clusters 1a–3a, 1b, 2b, 1c and 3c were isolated from the reactions of Ru3(CO)12 with two equivalents of the corresponding ketones 1–3; 4a and 5a were collected by adding 4 and 5 to Ru3(CO)12 in molar ratios of 1 : 1 and 1 : 3, respectively; 5b was obtained by adding 5 to 5a in a molar ratio of 2 : 1. All compounds were characterized by NMR, FT-IR, and MS-ESI, and most of them were structurally verified by single crystal X-ray diffraction. Although the reaction products of 1–3 and Ru3(CO)12 exhibit similar cluster frameworks of usual ruthenoles and CO-inserted binuclear clusters, the isolation of the clusters 1b–2b, 1c and 3c reveals their strong dependence on both electronic and steric effects of the substituents of the 1,3-ynones 1–3. In addition, detailed investigations suggested that the high reactivity of the terminal hydrogen atom and electron-withdrawing property of the carbonyl group in 4 play a key role in the formation of 4a, and that the structurally unusual 5a is an intermediate in the formation of 5b.

A novel copper-catalyzed cyclization of readily available vinyl azides with gem-difluoromethylene is described. This protocol is highly efficient and regioselective for assembling diverse trisubstituted pyridines in good to excellent yields, in which gem-difluoromethylene acted as a C1 precursor with a carbonyl group via triple cleavage and vinyl azides played a pivotal dual role.

The direct C-H functionalization of ethyl acetates was developed, delivering a variety of 1-(4-oxochroman-2-yl)ethyl acetate derivatives by reacting with chromones. This reaction has a wide substrate scope with excellent site-selective C-H activation at the inactive α-hydrogen of the alkoxyl group instead of the α-hydrogen of the carbonyl group under radical conditions. Compared with other protocols for the α-alkoxyl C-H functionalization of alkyl esters, a distinguishing feature of this reaction is that no metal catalyst was required, with DTBP as the sole oxidant.

We propose a carbonyl umpolung strategy for activating tropone as a normal-electron-demand Diels–Alder diene. Tropone has low reactivity for Diels–Alder reactions because of its [4n+2] π-aromaticity. Conversion of the carbonyl group into a hydrazone ion (=N–NR(−)) reverses the polarity of the exocyclic double bond, increases the [4n] ring π-antiaromaticity, and raises the HOMO energy. Computed gas-phase activation free energies for a Diels–Alder reaction with maleimide suggest a billion-fold rate increase when the tropone C=O is replaced by =N–NR(−) (R = H or SO(2)CH(3)). Other nonbenzenoid aromatics can be activated as normal-electron-demand Diels–Alder dienes in the same way.

This paper describes a selenium-promoted electrophilic cyclization of arylpropiolamides allowing the synthesis of 3-organoselenyl spiro[4,5]trienones via a 5-endo-dig ipso-mode. The 3-organoselenyl-quinolinone derivative formation via 6-endo-dig was avoided using an electrophilic organoselenium species in a metal-free protocol. The use of phenylselenyl bromide (1.3 equiv.), as the electrophilic source, in nitromethane (3 mL) at 90 °C enabled the cyclization of N-(2-methoxyphenyl)-N-methyl-3-phenylpropiolamides, giving 3-organoselenyl[4,5]triene-2,6-dione derivatives. The extension of the standard conditions to the N-(4-methoxyphenyl)-phenylpropiolamides led to the corresponding 3-organoselenyl spiro[4,5]trienones having the carbonyl group at the 8-position. Besides, we demonstrated a general application of our approach by using 3-organoselenyl spiro[4,5]trienones as substrates in Suzuki cross-coupling reactions, which gave the cross-coupled products in good yields.

The reaction mechanisms of [3+2] cycloaddition (32CA) between the α,β-unsaturated selenoaldehyde with nitrone and nitrile oxide were investigated theoretically using the molecular electron density theory (MEDT). Selenoaldehyde has two unsaturations which allow for the cycloaddition occurring. It was expected to undergo four regioisomeric reaction paths in two separate reactions with nitrone and nitrile oxide. The study was conducted using ab initio approach at MP2/6-31G(d) level of theory. Potential energy surfaces were generated from the energies of the stationary points involved in the mechanisms and the dominant reaction pathways were identified. It was found that Pathway 3 and 4 are the two competing reaction channels, where the cycloaddition reaction occurs at the selenium-analogue carbonyl group of selenoaldehyde. The reactivity indices were analysed at the ground state of the reactants to predict the reactivity of studied organic molecules in 32CA reactions. Analysis of the electronic structure of nitrone and nitrile oxide, the three-atom-components (TACs), and their participation in 32CA reactions towards selenoaldehyde allows establishing a useful classification of 32CA reactions into zwitterionin-type (zw-type) reactions involving TACs with a high zwitterionic character. Resumen. Se estudia teóricamente, utilizando la teoría de la densidad electrónica molecular (MEDT), el mecanismo de reacción de la cicloadición [3+2] (32CA) entre selenoaldehídos α, β insaturados con nitrona y óxido de nitrilo. El selenoaldehído tiene dos insaturaciones que permiten la cicloadición. Se esperaba que la reacción se llevara a cabo a lo largo de cuatro caminos regioisoméricos en dos reacciones separadas con la nitrona y el óxido de nitrilo. Se realizó un estudio ab initio con el nivel de teoría MP2/6-31G(d). Se generaron superficies de energía potencial a partir de las energías de los puntos estacionarios involucrados en el mecanismo y se identificaron los caminos de reacción dominantes. Se encontró que dos rutas, la 3 y la 4, son los canales de reacción que compiten para que ocurra la cicloadición en el grupo carbonilo análogo al selenio del selenoaldheído. Se analizaron los índices de reactividad de los estados basales de los reactivos para predecir la reactividad de las moléculas orgánicas estudiadas en las reacciones 32CA. El análisis de la estructura electrónica de la nitrona y el óxido de nitrilo, de las componentes triatómicas (TACs) y de su participación en las reacciones 32CA hacia el selenoaldheído permite clasificar a las reacciones 32CA en tipo zwitteriónico (zw) que involucran a los TACs con un elevado carácter zwitteriónico.

The reaction of 4-benzoyl-5-phenylamino-2,3-dihydrothiophene-2,3-dione (1) with aminoheteroaryls, lamotrigine, 1,3-diaminoheteroaryls, dapsone, NH2R (hydroxylamine, DL-1-phenylethylamine, and metformin), and 4,4′-bipyridine in THF/H2O (1 : 1) at room temperature led to 3-N-phenylthiocarbamoyl-2-butenamides 2–5, while that with naphthylamines and 1,3-phenylenediamine in ethanol at high temperature led to 5-phenylamino-2,5-dihydrothiophene-2-ones 6–8 as organic ligands in the medium to good yields. These showed the nucleophilic attacks of N-nucleophiles, except primary aromatic amines, on thioester carboxyl group (C-2) of thiophene-2,3-dione ring 1. However, the nucleophilic attacks of primary aromatic amines on the carbonyl group (C-3) of thiophene-2,3-dione 1 occurred in the form of substituted thiophenes.

A simple method for the synthesis of β-CF3 ketones through copper/silver cocatalyzed oxidative coupling of enol acetates with ICH2CF3 has been developed. Enol acetates were chosen as the source of carbonyl group, giving the β-CF3 ketones in moderate yields. Control experiments imply that a radical process maybe involved in this reaction.

We demonstrate that the synthesis of 5-methoxy-2,2,5-trialkyl-substituted 2,5-dihydrofurans containing unprotected hydroxymethyl group at the C-2 position involves aromatization via fragmentation involving С–С bond cleavage, resulting in the formation of 2,5-disubstituted furans and carbonyl compounds. 2,5-Dihydrofurans bearing an ester group at the С-2 position were stable. It was found that 2,2,5-trialkyl-substituted 2,5-dihydrofurans containing a hydroxymethyl or carbonyl group in the side chain could aromatize through auto-oxidation, which was facilitated by adjacent functional groups (sulfo- or pivaloyl groups).

A series of novel azo group fused 2 H-chromenes and 4 H-chromenes were synthesised as well as pyranopyrazole derivatives via the Knoevenagel condensation reaction of C–H acid compounds with 5-(arylazo)salicylaldehydes by a nucleophilic addition to the carbonyl group followed cyclisation.

A novel copper-catalyzed intermolecular carboesterification strategy of alkenes with α-carbonyl alkyl bromides is described. This reaction represents a facile and straightforward access to polysubstituted γ-lactone skeletons, including γ-lactones having ortho-substituted groups on the carbonyl group, in moderate to good yields via a radical strategy, which has good functional group tolerance.

The purpose of this study was to evaluate the influence of oligochitosan (COS) as amino (–NH2) or carbonyl group (–C=O) donors on the antioxidant activities of COS Maillard reaction (MR) products. Two kinds of COS MR products (COS MRPs) were prepared by using COS and glucose/α-alanine, respectively. Their structures were characterized by Fourier transform infrared spectroscopy (FT-IR), their molecular weights (Mws) were measured by gel permeation chromatography, and the –NH2 contents of COS MRPs were determined. The antioxidant activities of COS MRPs were evaluated by measuring the scavenging activity of superoxide anion radical (O2−), 1,1-diphenyl-2-picrylhydrazyl radical, and the reducing power. The result showed that C=N absorbance can be observed in CG (MRPs of COS and glucose) and CA (MRPs of COS and α-alanine). The Mw of COS increased after MR. CG and CA showed dramatically enhanced antioxidant activity compared to COS, and the antioxidant activity of CG was better than that of CA. In other words, MR is an efficient way to enhance the antioxidant activity of COS. Moreover, it is a more efficient way to enhance the antioxidant activity of COS by using COS as amino group donor involved in MR. The results may provide some references to the modification and application of COS.

A ring-opening [3+2] annulation reaction between cyclopropenones and amides was developed to produce 5-amino-2-furanones. Insertion of the carbonyl group of an amide to the C–C single bond of a cyclopropenone occurred efficiently in the presence of a catalytic amount of silver(I) triflate.

O2-Phosphodiesterification of xanthosine has been achieved by a one-pot procedure consisting of the phosphitylation of the 2-carbonyl group of appropriately protected xanthosine derivatives using phosphoramidites and N-(cyanomethyl)dimethylammonium triflate (CMMT), oxidation of the resulting xanthosine 2-phosphite triesters, and deprotection. In addition, a study on the hydrolytic stability of a fully deprotected xanthosine 2-phosphate diester has revealed that it is more stable at higher pH.

A rhodium-catalyzed C-H amination of benzamides and isoquinolones with anthranils has been realized under assistance of a weakly coordinating tertiary amide, leading to a bifunctional amination product bearing a proximal carbonyl group. N-benzoylpyrrolidine and N-substituted isoquinolones are two classes of amides that are applicable. The aminated products can further cyclize to acridine under in situ or ex situ conditions.

The first example for the generation of carbonyl ylides from palladium carbenes is reported. Systematic investigation of the substituents attached to the carbonyl group indicates that the employment of trifluoromethyl group as the substituent is very critical for the success of this transformation. The remarkable fluorine effect on thereactivity is very impressive, which allows to the construction of various trifluoromethylated oxiranes in high yields and diastereoselectivities.

This review highlights recent achievements in the transformations of 2-acylaziridines toward the synthesis of cyclic and acyclic nitrogen-containing compounds. The influence of a carbonyl group on reaction selectivity is discussed.1 Introduction2 Reactions via C–C Bond Cleavage3 Reactions via C–N Bond Cleavage3.1 Reactions Starting with the Aziridine Ring Opening3.2 Reactions Starting at the Carbonyl Group4 Conclusion

The 5’-alkynylation of uridine-derived aldehydes is described. The addition of alkynyl Grignard reagents on the carbonyl group is significantly influenced by the 2’,3’-di-O-protecting groups (R1): O-alkyl groups led to modest diastereoselectivities (65:35) in favor of the 5’R-isomer, whereas O-silyl groups promoted higher diastereoselectivities (up to 99:1) in favor of the 5’S-isomer. A study related to this protecting group effect on the diastereoselectivity is reported.