Tetracyanoethylene tricyanovinylation with

Tetracyanoethylene yields a colored it-complex with aromatic compounds in the case of aromatic amines, phenols and indoles these then react to yield the corresponding tricyanovinyl derivatives [3, 4]. 

Methyl-2-(2-thienyl)pyrrole 686 (X = S) reacted with tetracyanoethylene to yield the 3-tricyanovinyl isomer 687 along with 4-tricyanovinyl derivative 688 (Equation 165) <2001ARK37>. Under these conditions, 2-(2-furyl)-5-methylpyrrole 686 (X = O) behaved differently, namely, the major direction of the reaction with tetracyanoethylene involves the attack on the a-position of the furan ring giving rise to product 689 (Equation 165) <2001ARK37>. 

Tricyanovinyl-N,N-dimethylaniline has been prepared by adding hydrogen cyanide to -dimethylaminobenzalmalono-nitrile and oxidizing the adduct.3 The present procedure, an adaptation of one that has been published,3 is the more convenient preparative method. It can be applied to a wide variety of secondary and tertiary aromatic amines to give />-tricyanovinyl-arylamines that, like the present one, are dyes.3 Other types of aromatic compounds also condense with tetracyanoethylene in this manner. Thus one can obtain 4-tricyano vinyl-2,6-dimethyl-phenol from 2,6-dimethylphenol, 2-tricyanovinylpyrrole from pyrrole, and 9-tricyanovinylphenanthrene from phenanthrene.4... 

Reaction with tetracyanoethylene. McKusick and Melby added tetracyano-ethylene in portions to a stirred solution of dimethylaniline in dimethylformamide while controlling the temperature to 45-50°. p-Tricyanovinyl-N,N-dimethylaniline... 

The purple charge-transfer complex of indole with tetracyanoethylene decomposes in neutral or basic media to the 3-substituted indole (164), whereas under acidic conditions the 2-(tricyanovinyl)-isoraer is formed. The cyclo-adducts of l-benzyl-3-vinylindole to tetracyanoethylene and maleic anhydride are the cyclobutane (165) and the tetrahydrocarbazole (166), respectivelyThe reaction of 9-methyl-l,2,3,4-tetrahydrocarbazole (167) with dimethyl acetylenedicarboxylate in aqueous acetic acid yields a mixture of the bridged compounds (168) and (169). The photo-adduct (170) of methyl acrylate to 1-benzoylindole rearranges to the benzazepine (171) in hot xylene... 

New Applications of Tetracyanoethylene (TCNE) in Organic Chemistry, A. J. Fatiadi (1986). This review with 501 references deals with reactions of tetracyanoethylene used in organic synthesis. Information on molecular complexes, ozonization of alkenes and acetylenes, dehydrogenation and tricyanovinylation, reactions of TCNE oxide, reactions with ketones and diketones, synthesis of heterocycles and cationic polymerizations are included in this survey. Some industrial and analytical applications are also discussed. 

Lithiation of thieno[3,2- )]thiophenes 145a, b gives 2-lithium derivatives, whose treatment with chalcogens and iodomethane affords chalcogenides 159 (96JCS(P2)1377). Vilsmeier-Haack formylation of the latter produces aldehydes 160, whereas the reaction with tetracyanoethylene (TCNE) in DMF affords 5-tricyanovinyl derivatives 161. 

It is interesting to note in this connection that the reaction of 2-methyl-5-(2-thienyl)pyrrole with tetracyanoethylene gives rise to both 3- and 4-tricyanovinyl-5-(2-thienyl)pyrroles (90% total yield, 5 1 isomer ratio [Scheme 2.29, Table 2.3]) [445]. 

N-Methylpyrroles react with tetracyanoethylene in various solvents (acetone, tetrahydrofuran (THF), dimethylsulfoxide(DMSO)) nonselectively to form mixtures of 3-, 4-, and 5-tricyanovinylpyrroles (Scheme 2.31, Table 2.3) [448,449]. However, in the presence CuBr-LiBr complex (soluble in THF), the reaction proceeds regioselectively to give exclusively the products of tricyanovinylation at a-position of the pyrrole ring [448]. 

However, N-vinyl- and N-isopropenyl-3-tricyanovinyl derivatives (more than 90% yields) are the only products of the reaction between N-vinyl- and N-isopropenyl-2-methyl-4,5,6,7-tetrahydroindoles with tetracyanoethylene in DMSO (Scheme 2.32, Table 2.3) [445]. 

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