Regioselectivity in the 1, 3??dipolar cycloaddition reaction of unsymmetric pyridinium dicyanomethylides with dimethyl acetylenedicarboxylate and methyl propiolate: …
Abstract A study of the cycloaddition behavior of a series of unsymmetric pyridinium dicyanomethylides with dimethyl acetylenedicarboxylate and methyl propiolate has been carried out. The 1, 3-dipolar cycloaddition proceeds in good yield with high regioselectivity to produce the corresponding indolizines and 1: 1 adducts. The reactions of isoquinolinium dicyanomethylide follow frontier orbital predictions. In contrast, polar 3-substituted ...