SYNTHESIS OF ,7-HEXAHYDROIMIDAZO-[1,2-A]PYRINE-8-CARBONITRILES, AHYDRO-1H-PYRIDO[1,2-A]PYRIMIDINE-9-CARBONITRILES, AND AHYDROPYRIDO[1,2-A][1,3]DIAZEPINE-10-CARBONITRILES

A simple method for the synthesis of the title compounds is described. Thus, alpha,beta-unsaturated esters (1) are transformed in the alread y described y-6-oxo-1,4,5,6-tetrahydropyridine-3-carbonitriles (3) whi ch are treated with NH2(CH2)(n)NH2 (n = 2, 3, 4) to afford the corresp onding bicyclic compounds (4, 5, and 6). The nitrogen bridged nature o f these compounds is determined by an X-ray structure analysis of 4b. A ring opening-ring closure mechanism is proposed for the formation of structures (4-6) on the basis of the reaction between 3b and N-15,N-1 5'-ethylenediamine which afforded N-15,N-15'-4b.