Regioselechve Reaction of α－（Alkoxydimethylsilyl）allyl Carbanions with Alkyl Halides and Aldehydes

The reactions of α-(alkoxysilyl)allyl anions 4 with electrophiles were studied. α-Alkylation with alkyl halides was favoured, whereas γ-selection was achieved in the reaction with aldehydes.

Ketone Synthesis by Direct, Orthogonal Chemoselective Hydroacylation of Alkenes with Amides: Use of Alkenes as Surrogates of Alkyl Carbanions

Summary of main observation and conclusion Direct functionalization of alkenes and direct transformation of carboxamides are two exciting areas that have attracted considerable attention in recent years.We report herein that secondary amides,the least reactive derivatives of carbonyl compounds,upon activated with triflic anhydride,can serve as effective hydroacylating reagents in partner with alkenes to yield ketones at ambient temperature.The method was applied to the one-step synthesis of racemic dihydro-ar-turmerone.In this method,alkenes serve as surrogates of organometallic reagents,which allows the orthogonal chemoselective reactions.The ready availability of many olefins such as camphene and norbornene permits one-step ketone synthesis that would require several steps by conventional methods.

Cross-Coupling of Secondary Amides with Tertiary Amides: The Use of Tertiary Amides as Surrogates of Alkyl Carbanions for Ketone Synthesis

In recent years,exciting progress has been made in the field of direct transformation of amides,nevertheless,the condensation between two amides remains rare and restricted to homo-coupling reactions.Herein,we report the cross-coupling of secondary amides with tertiary amides,which provides a synthesis of ketones under mild conditions,and features the use of tertiary amides as surrogates of alkyl carbanions.The method relies on the coupling of enamines,generated from tertiary amides by catalytic partial reduction of tertiary amides with Vaska's catalyst,with nitrilium ions,formed in situ from secondary amides via activation with trifluoromethanesulfonic anhydride,and on the subsequent deformylation.

Studies on organophosphorus compounds 104. Reaction of carbanions derived from alkylphosphonates

Structural effect of substituents directly bonded to carbanions bearing a phosphorate moiety is examined. Nucleophihc addition of phosphonate carbanion to 1-nitroalkene followed by subsequent reaction with chlorotrimethylsilane leads to a series of 2-isoxazoline based on the formation of an alkene and silyl nitronate as a 1,3-dipole. On the other hand, addition of carbanion derived from isocyanomethylphosphonate to nitroalkene with the formation of nitronate followed by intromolecular cyclization provides substituted phosphoryl pyrroles.

(Et_4N)_2[Fe_4(SPh)_10] Stimulated S_(RN)1 Reactions of α-Bromonaphth-alene with Pinacolone Carbanion

The (Et_4N)_2[Fe_4(SPh)_10] stimulated reaction of α-bromonaphthalene with pinacolone carbanion in DMSO leads to the formation of 1-(α-naphthyl)pinacolone. The reaction is suggested in terms of SRN1 mechanism of aromatic nucleophillic substitution and has potential value in synthesis to obtain (-substituted naphthalene derivaties.

Synthesis of 6-(Bromomethyl)-4-methoxy-5,6,7,8-tetrahydropyrido-[3,2-d]pyrimidin-2-ol from 6-Methylpyrimidine-2,4-diol

6-（Bromomethyl）-4-methoxy-5,6,7,8-tetrahydropyrido[3,2-d]pyrimidin-2-ol（compound 9） was synthe sized from 6-methylpyrimidine-2,4-diol（compound 1） through the crucial steps of 6-methyl alkylating and intramo lecular cyclization. The assignment of the structure of compound 9 was performed by its spectral data, 1H NMR, 13C NMR, HMBC, and HRMS spectra.

Ab Initio Studies on MCH_2(OH) and CH_3OM(M=H, -, Li, Na)

MCH 2(OH) and CH 3OM(M=-, Li, Na) were calculated by means of ab initio method at the MP2/631+G* level. The results show that the metals have the ability to localize charge on O in CH 3OM(M= Li, Na). MCH 2(OH)(M=Li, Na) has four possible structures, among which carbonoxygenbridged structure 1 is the most stable and observable kinetically. For MCH 2(OH)(M=Li, Na), the existence of the metal increases the rigidity of the carbon configuration. This may be the reason why MCH 2(OR)(M=Li, Na) is widely used in stereoselective syntheses.

On the Absolute Configuration of Schweinfurthinol

Through the chiral-pool based synthesis of both enantiomers of schweinfurthinol, it has been proven that this natural product isolated from the seeds of Canarium schweinfurthii possesses an （S） configuration. The optical rotation data for pure schweinfurthinol is also updated.

Base initiated halogen-exchange reactions between perhaloalkanes

Halophilic attacks on C-X bonds (X=Br,Cl) by a base can easily initiate mtermolecular bromme-chlonne exchange reactions either among bromine-or chlorine-containing perhaloalkane molecules of different compounds of among molecules of the same compound It provides a new and convenient method to synthesize perhaloal-kanes Apparently,it pertains to an amomc mechanism,i e.the reaction is initiated by halophilic attack on C-X bonds by the base,and an intermediate carbanion is formed.Distributions of the products depend on the equilibria involving all carbanion intermediates and perhaloalkane product molecules.

Hetero diacylation of 1,1-diborylalkanes:Practical synthesis of 1,3-diketones

An efficient protocol for the synthesis of asymmetric 1,3-diketones was reported through diacylation of1,1-diborylalkanes using two different acyl sources.In this transfo rmation,an enolate boron species was initially formed by introducing an acyl group,then it was trapped by another acyl group to form 1,3-diketone.This method not only provided the gateway to obtain a series of 1,3-diketones,but also afforded an operationally simple and efficient access to pyrazoles and isoxazoles.

Base-Promoted Catalyst-Free Regioselective Hydroacylation of Styrenes with Hydrazones via Carbanion Addition

Wereport a base-promoted catalyst-free protocol for the highly regioselective hydroacylation of styrenes with hydrazones derived from naturally abundant aldehydes.This protocolgeneratedlinearketoneswith goodfunctional grouptolerance anda broadsubstrate scope under mild conditions.Mechanistic studies showed that the addition of hydrazone anion to a styrene double bond was the key step,different from previoushydroacylationpathways(viaorganometallic complexes or radical intermediates).

Nucleophilic Substitution Reaction of p-Dinitrobenzene by a Carbanion: Evidence for Electron Transfer Mechanism

On the basis of investigation of cyclic voltammetry, EPR spectroscopy and competition experiments, the nucleophilic substitution reaction of p- dinitrobenzene with the sodium salt of ethyl α-cyanoacetate carbanion in dimethyl sulfoxide giving ethyl α-cyano-α- (p-nitrophenyl) acetate is shown to take place via the intermediacy of p-dinitrobenzene radical anion. The reaction rate goes faster than that between p-nitrohalobenzenes and the same sodium salt of ethyl α-cyanoacetate carbanion. There is an evidence for a single electron transfer mechanism.