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

General Papers ARKIVOC 2006 (ix) 292-365 XC6H4-C(Cl)=NNHPh EtOH, Et3N Me O Me O Ph +- N N XC6H4-C=N-N-Ph N CN NO O N N 219 R R H CN C6H4X Ph X = Me ,Cl 220 N R = Ac, Bz MeNHCO N - R-N=C=O CN C6H4X 221 Scheme 80 The reaction of 1-ethoxycarbonylmethylene-3,4-dihydro-6,7-dimethoxy-isoquinoline (222) with C,N-diphenylnitrilimine in chloroform was reported to yield 223 in 80% yield instead of the expected 1,3-adduct 224.87 However, reaction of 222 with C-acyl-N-arylnitrilimines gave the respective 5,6-dihydropyrrolo[2,1-a]-5,6-dihydroisoquinolines (225) in 78-82% yields.87 Further evidence is required to confirm the structure of the claimed product 225 and to explain why the regiochemistry of C-diphenylnitrilimine is different from that of C-acylnitrilimines in their reactions with 222 (Scheme 81). ISSN 1424-6376 Page 346 ©ARKAT