Functionalized Enamines in the Synthesis of Some Heterocyclic Compounds

Esters of 3-amino-2-cyanoacrylate and analogous compounds were used as starting material for pyridines which were obtained via the corresponding amidines.On the other hand, from ethyl 5-arninoisoxazole-4-carhoxylate or 5-amino-4-cyanoisoxazole in a similar reaction sequence a pyrimidine derivative could be prepared.The principal synthesis of pyrimidines from acylic precursors is the condensation of an N-C-N and a C3 fragment.lt2The synthesis of a pyrimidine ring from C3-N and C-N fragments has been used less frequently and in most cases alkyl or aryl imidates have been used as synthons and representing the C-N fragment.By this approach, pyrimidines were synthesized from derivatives of 3-arninoacrylic acid and isocyanates or isothiocyanates, 3-9 , .lmldates and imidoyl chlorides.12