Dicyanomethylene compounds

Dicyanomethylene compounds react with ethoxy cation 75 in the presence of DIPEA to form triafulvenes 95 87, 88. The same is true for 1,3-bis(dicyanomethylene)-indane and cyanomethylene dimedone, from which the sterically crowded vinylogous triafulvenes 96 and 97 were prepared88). 

Dicyano-substituted triafulvenes react with enamines to produce exclusively the cross-conjugated dicyanomethylene compounds 519, whose formation can be rationalized by a methylene bicyclo(2,l,0)pentane intermediate 51879 296 Since cyclanone enamines 520 and other cyclic enamines 522 react analogously, this C-C-insertion 237) of the triafulvene ring skeleton into the enamine C=C bond represents a versatile ring expansion mode (C + C3), which makes accessible a series of unsaturated medium-ring compounds (521/523) that are otherwise difficult to synthesize. 

Reactions of Malononitrile Derivatives, F. Freeman (1981). Preparation, spectral properties, and chemical reactivity of dicyanomethylene compounds halomalononitriles, aminomalononitrile, aminomethylenemalononitrile, alkoxymethylenemalononitriles, hydroxyiminomalononitrile, (0-/7-tosylnitroso)malononitrile, and arylhydrazonomalono-nitriles are reviewed (367 references). Their use for the preparation of cyanocarbons and heterocyclic systems is described. 

Cyclization ofYlidenemalononitriles, E. Campaigne and S. W. Schneller (1976). The use of malononitrile in annelation reactions (via intermediate dicyanomethylene compounds)... 

Properties and Reactions of Ylidenemalononitriles, F. Freeman (1980). Dicyanomethylene compounds, their molecular structure and spectral properties, toxicity and analyses are reviewed. Various reactions like hydrolysis, oxidation and reduction, dimerizations, cyclizations, photochemistry and thermolysis are discussed. The review, which contains 380 references, also deals with unsaturated compounds, oxygen, nitrogen, phosphorous and sulfur compounds. 

Reactions of the methylene group Reactions at the methylene group of the molecule yield dicyanomethylene compounds in many cases. These will be discussed in Section III. A. 3 in detail. Some compounds have been reported, which result from reactions at the methylene group of 10 but are no classical dicyanomethylene compounds. So, for example, nitrosation with nitrous acid in the presence of nucleophilic catalysts yielded the corresponding oxime product (NC)2C=N0H42. 

TABLE 4. Preparation of bis(dicyanomethylene) compounds (without TCNQ derivatives)... 

Sulphur heterocycles. a-Haloketones 296 were reacted with (dimercaptomethylene) malononitrile297to form thienothiophenes298. Cyclocondensation of dicyanomethylene compound 299 with 300 gave benzothiin derivatives 301. ... 

From 417 on reaction with the dithiocarboxylate 418, the dicyanomethylene compound 419 was formed which, when refluxed with a base, afforded 420. 417 and pyrimidine 421, when reacted in ether, gave A -dicyanomethylide 422 in 60% yield. 422 has been used for various cycloadditions. ... 

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