Synthesis of 4H-cyclohepta[b]thiophen-4-ones, 4H-cyclohepta[b]furan-4-one, and 9H-cyclohepta[b]pyridin-9-one

Abstract

The title compounds have been prepared by dehydrobromination of αα-dibromocycloheptanones, using lithium salts in boiling dimethylformamide. Conversion of 6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine into 5,6,7,8-tetrahydro-9H-cyclohepta[b]pyridin-9-one (20) was achieved viathe N-oxide (21) and the 9-hydroxy-derivative (23).