Synthesis of pyrrolo[1,2-]quinolines by formal 1,3-dipolar cycloaddition reactions of quinolinium salts.

Quinolinium salts, Q-CH-COMe Br and Q-CH-CONMe Br (where Q = quinoline), were prepared from quinolines. Deprotonation of these salts with triethylamine promoted the reaction of the resulting quinolinium ylides (formally azomethine ylides) with electron-poor alkenes by conjugate addition followed by cyclization or by [3 + 2] dipolar cycloaddition. The pyrroloquinoline products were formed as single regio- and stereoisomers.