REACTIONS OF THE DERIVATIVES OF (DIPHENYLMETHYLENE-AMINO) ACETIC-ACIDWITH CARBON-DISULFIDE AND PHENYL ISOTHIOCYANATE AND CRYSTAL AND MOLECULAR-STRUCTURE OF METHYL IPHENYLMETHYLENE-AMINO)-2-(1,3-DITHIANE-2-YLIDENE) ACETATE

Derivatives of (diphenylmethylene-amino) acetic acid 1-3 react in the presence of bases (NaH, t-BuONa) or under phase transfer conditions wi th carbon disulfide to give the corresponding ketene dithioacetals 4- 11 after alkylation. Phenyl isothiocyanate and dicyclohexyl carbodiimi de give rise to ketene-S,N- and N,N-acetals. Methyl diphenylmethylenea mino)-2-(1,3-dithiane-2-ylidene) acetate (7) was characterized by an X -ray structure determination. The compound has a 2-aza-1,3-butadiene f ragment containing two well localized double bonds. The C = N - C = C group is significantly non-planar, the relevant torsion angle amounts to -103.5(3)degrees.