A NEW APPROACH TO THE CHEMISTRY OF SPIROHETEROCYCLES

Interaction of alpha, alpha-dibromodiethylmalonate (1) with 4-substitutcd thiosemicarbazides (2) in the presence of a base afford 2,2'-dialkyl/arylimino-octahydro-6,6'-spiro-bi[1,3,4-thiadiazine]-5,5'-diones (4). However, in the absence of base diethyl bis[N-aminocarbamylmercapto]malonate (6) is obtained exclusively. Similarly the reactions of 1 with 1-phenyl-4-substituted thiosemicarbazides (2, R(1) Ph) are reported. Interaction of 1 with thiosemicarbazides in the presence of thiocarbamides afford 2-alkyl/arylimino-6-carbethoxy-6-(N-alkyl/arylisothiocarbamido)-1,3,4-thiadiazin-5-ones (8/9)