A simple method for the synthesis of the title compounds is described. Thus, α,β-unsaturated esters (1) are transformed in the already described 2-methoxy-6-oxo-1,4,5,6-tetrahydropyridine-3-carbonitriles (3) which are treated with NH2(CH2)nNH2 (n = 2, 3, 4) to afford the corresponding bicyclic compounds (4, 5, and 6). The nitrogen bridged nature of 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 15N,15N′-ethylenediamine which afforded 15N,15N′-4b. © 1995.
|Publication status||Published - 1 Oct 1995|