名称:
Sodium 2-Cyanoethylene-1,1-dithiolate Tetrahydrate: a Stable Salt of Cyanodithioacetic Acid. A New Preparative Route to 2-Cyanoketene S,S-, S,N- and N,N-Acetals.
摘要:
2-Cyanoethylene-1,1-dithiolate, the dianion of cyanodithioacetic acid, is prepared from ethyl cyanoacetate by condensation with carbon disulfide followed by hydrolysis and decarboxylation with sodium hydroxide. The anion has been isolated and characterized as a stable, tetrahydrated sodium salt (2) and alkylated to give 3,3-bis(alkylthio)propenonitriles (3) in excellent yields. Alkylation of an intermediate, unstable trianion of 2-cyano-1,1-dithiomalonic acid (4) gives 3,3-bis(methylthio)-2-cyanopropenic acid (6a) which on treatment with mono- and di-alkylamines undergoes consecutive substitution and decarboxylation to 3-amino-3-(methylthio)propenonitriles (7). The application of 1,2-diamines or 2-aminoethanethiol leads to cyclized products, (imidazolidin-2-ylidene) acetonitriles(9) and (1,3-thiazolidin-2-ylidene)acetonitrile (10), respectively.