Reactions of nitrilimines with heterocyclic amines and enamines. Convenient methodology for synthesis and annulation of heterocycles

General Papers ARKIVOC 2006 (ix) 292-365 Ph-C(Cl)=N-NH-Ph R'COC(Cl)=N-NH-C6H4X EtOH, Et3N EtOH, Et3N + - + - MeO N R'COC=N-N-C6H4X Ph-C=N-N-Ph MeO H CHCOOEt 222 MeO MeO MeO N N H MeO MeO H MeO NR' NNHPh N N=CHPh EtOOC EtOOC N EtOOC N C6H4X 223 Ph Ph 224 225 X = H, Me R’ = Me, Ph, 2-thienyl, 2-naphthyl Scheme 81 The reaction of C,N-diphenylnitrilimine with the exocyclic enamine 226 led to a mixture of 227 and 228 in 36-38% and 23-39% yields, respectively.88 The latter product 228 was assumed to be formed via cycloaddition to the carbonyl group followed by opening of the 1,3,4oxadiazoline ring and recyclization.85 When the products 227 were refluxed in trifluoroacetic acid, they underwent ring cleavage to give the respective 229 in 36-38% yields (Scheme 82).88 ISSN 1424-6376 Page 347 ©ARKAT