The chemistry of cyanoacetylenes. Part V. 1,3-Dipolar cycloaddition reactions of cyanoacetylenes with N-ylides and N-imines

Abstract

1,3-Dipolar cycloaddition reactions of zwitterionic pyridinium, quinolinium, and isoquinolinium phenacylides with cyanoacetylene or chlorocyanoacetylene afforded 1-cyanoindolizine derivatives. Similar reactions of N-aminopyridinium and isoquinolinium salts gave 3-cyanopyrazolo[1,5-a]pyridine derivatives. A 3-methylpyridinium ylide reacted with the same dipolarophiles at the 2-position, in spite of hindrance by the methyl group. Reactions of cyclopentadien ylides with cyanoacetylenes gave trans-2-(2-cyanovinyl)cyclopentadienylides.