Reactions of Heteroaryl Substituted Propenones

Summary.

Thienyl- and furylpropenones reacted with malonates, cyanoacetates, and malononitrile giving addition products which could be cyclized to heteroaryl substituted dihydropyranes, cyclohexanols, and piperidones. Heteroaryl substituted cyclopropyl ketones were prepared by reactions with Me₃SO⁺ I⁺, and by reaction with Lewis acids they were transformed into substituted dihydrobenzo[b]furanone or -thiophenone, or γ-hydroxy ketones. Cycloadditions with thiophene derivatives allowed the synthesis of substituted benzo[b]thiophene derivatives, but with poor yields. Structures and stereochemistry were established mainly by means of NMR spectroscopy.