Nitriles from benzylic compounds

On the other hand, optically active 43 and 44 were synthesized as follows.401 Treatment of 2,3,4-tri-0-benzyl-l,5-di-0-tosyl-D-arabinitol (277) with three equimolar proportions of methylenetriphenylphos-phorane gave the cyclic phosphorane (278), which was stereoselectively converted into the cyanohydrin (279) by way of the corresponding C-methylene and inosose derivatives. Compound 279 was converted into 43 and 44 by way of the corresponding carboxylic acid (280), and unsaturated nitrile (281), respectively. Compound 39 was derived from the inosose (282), obtained from quebrachitol, through a 21-step conversion.402 Introduction of a hydroxymethyl group into 282 was accom-... 

A one-pot synthesis of 3,5-disubstituted 7-hydroxy-3//-l,2,3-triazolo[4,5-d]pyrimidines (130) has been carried out by using benzyl azide, cyano-acetamide, ethyl or methyl esters of the appropriate carboxylic acid, and sodium ethoxide as catalyst. The reaction proceeds via a 5-amino-l-benzyltriazole-4-carboxamide intermediate (85JHC1607). 7-Amino-3H-l,2,3-triazolo[4,5-d]pyrimidines 133 (R2 = H) were prepared starting from benzyl azide, malononitrile, and an aliphatic or aromatic nitrile, or by reaction of 130 with phosphorus oxychloride followed by amination. Compound 132 was formed in most reactions from two molecules of the 5-amino-4-cyano-l-benzyltriazole intermediate by an intermolecular nucleophilic at-... 

Another route to 5-amino-5-deoxy-L-idose proceeds from 5-(benzyl-amino)-5-deoxy-l,2-0-isopropylidene-R-L-idurononitrile (56), which is readily obtainable from 1,2-O-isopropylidene-a-D-xj/lo-pentodialdo-1,4-furanose (13) by reaction with benzylamine and hydrogen cy-anide. Partial hydrogenation of the nitrile 56 by the Kuhn procedure, in acid solution, leads to the hexodialdose (57), which is reduced with sodium borohydride to 5-amino-5-deoxy-l,2-0-isopro-pylidene-jS-L-idofuranose. From this compound, tbe acyclic bisulfite adduct (58) is obtained by reaction with sulfiirous acid. Treatment of 58 with barium hydroxide gives crystalline 5-amino-l,6-anhydro-5-deoxy-jS-L-idopyranose (60) in almost quantitative yield. The equilibrium between the pyranose form (61) and its 1,6-anhydride (60) lies far on the side of Ae bicyclic form (60). The equilibrium can be evaluated from the optical rotation of the solution obtained by treat-... 

Nickel peroxide, an undefined black oxide of nickel, is prepared from nickel sulfate hexahydrate by oxidation in alkaline medium with an ozone-oxygen mixture [929] or with sodium hypochlorite [930, 931, 932, 933]. Its main applications are the oxidation of aromatic side chains to carboxyls [933], of allylic and benzylic alcohols to aldehydes in organic solvents [929, 932] or to acids in aqueous alkaline solutions [929, 930, 932], and of aldehydes to acids [934, the conversion of aldehyde or ketone hydrazones into diazo compounds [935] the dehydrogenative coupling of ketones in the a positions with respect to carbonyl groups [931] and the dehydrogenation of primary amines to nitriles or azo compounds [936]. 

The required compound D could be envisaged to arise from acetylbenzene (made by Friedel-Crafts acetylation of benzene), followed by acid-catalyzed halogenation of the ketone (Section 18-3). Reduction of the nitrile group in compound C could be carried out with concomitant carbonyl conversion to give a primary amine version of compound A, namely, E. A-Methylation might be most conveniently accomplished by reductive amination (although, as we shall see in Chapter 22, the benzylic position may be sensitive to the reductive conditions employed). 

Optically active 3-arylisoxazoline-5-carboxylic acid derivatives 403 or 404 have been, prepared by the reaction of (S)- or (/ )-3-acryloyl-4-benzyl-5,5-dimethyloxazolidin-2-one (405 or 406) with nitrile oxides, obtained from benzo-hydroximoyl chloride and its substituted derivatives in the presence of a catalytic amount of metal salt, for example, Yb(OTf)3 (445). This procedure improves the diastereoselectivity of compounds 403 or 404, which are industrially useful as intermediates for various drugs and agrochemicals. It also enables the amount... 

Conversely, activated methylene compounds undergo an addition reaction across the C=N bond of imines. For example, benzylic ketones react with benzylidene anilines to from P-aminoketones [35], whereas the analogous reaction of diphenyl-methylene-protected a-amino esters, and nitriles, produces a disastereomeric mixture of the A-protected a,p-diamino esters, and nitriles [36, 37]. 

Decarboxylation of 1,3-dimethylorotic acid in the presence of benzyl bromide yields 6-benzyl-1,3-dimethyluracil and presumably involves a C(6) centered nucleophilic intermediate which could nonetheless have either a carbene or ylide structure. Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry has been used to explore the gas-phase reactions of methyl nitrate with anions from active methylene compounds anions of aliphatic ketones and nitriles react by the 5n2 mechanism and Fco reactions yielding N02 ions are also observed nitronate ions are formed on reaction with the carbanions derived from toluenes and methylpyridines. 

Cross coupling between an aryl halide and an activated alkyl halide, catalysed by the nickel system, is achieved by controlling the rate of addition of the alkyl halide to the reaction mixture. When the aryl halide is present in excess, it reacts preferentially with the Ni(o) intermediate whereas the Ni(l) intermediate reacts more rapidly with an activated alkyl halide. Thus continuous slow addition of the alkyl halide to the electrochemical cell already charged with the aryl halide ensures that the alkyl-aryl coupled compound becomes the major product. Activated alkyl halides include benzyl chloride, a-chloroketones, a-chloroesters and amides, a-chloro-nitriles and vinyl chlorides [202, 203, 204], Asymmetric induction during the coupling step occurs with over 90 % distereomeric excess from reactions with amides such as 62, derived from enantiomerically pure (-)-ephedrine, even when 62 is a mixture of diastereoisomcrs prepared from a racemic a-chloroacid. Metiha-nolysis of the amide product affords the chiral ester 63 and chiral ephedrine is recoverable [205]. 

From 2-mercaptobenzoic Acid. The most widely used method of 1,3-benzo-TA synthesis is the reaction of 2-mercaptobenzoic acid with compounds containing a cyano group to afford various 2-substituted 1,3-benzo-TAs 56 [aryl and benzyl (57MI1), chloromethyl, and carboethoxymethyl (60MI1)]. Note that nitriles of aliphatic acids (acetonitrile and others) do not react in these conditions. The reaction of 2-mercaptobenzoic acid with... 

Functionally substituted benzylic, allylic, and vinylic compounds containing alkoxides, esters, ethers, nitriles, or amides can be reacted with halosilanes under Barbier conditions using HMPT to yield C- and O-silylated products, 1,2- or 1,4-addition products, as well as reductive dimers. Radical and anionic intermediates are postulated, based on SET reactions from the metal, and multiple silated species can be obtained. The use of the TMSCl-Mg-HMPT system has been extensively investigated by Galas group [85] at the University of Bordeaux, and their work has greatly advanced the science of the Barbier reaction with silanes. 

In a general annulation method, 4-aminonicotinonitriles are treated with ethyl orthoformate to give the corresponding (ethoxymethylene)amino compounds. The nitrile group is then converted with sodium hydrogen sulfide into a thioamide function which cyclizes to yield the 2-sulfanylpyrimidine moiety. An application of this method is the synthesis of 6-benzyl-5,6,7,8-tetrahydropyrido[4,3-t/]pyrimidine-2-thiol (3) from l-benzyl-4-[(ethoxymethylene)amino]-l,2,5,6-tetrahydropyridine-3-carbonitrile (2).491 492... 

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