Transannular reactions of 5-azido- and 5-nitronodibenzo[a,e]cyclooctatrienes and -dibenzo[a,d]cycloheptatrienes. Syntheses of pavine and homoisopavine analogs

Abstract

In summary, the results reported here show that transannular cyclization and cycloaddition reactions of 5-substituted dibenzo[a,e]cyclooctenes 4,5, and 6 are more facile than those of the corresponding dibenzo[a,d]cycloheptenes 7, 8, and 9. This difference can be accounted for by formation of less strained transition states in the transannular reactions of the cyclooctene derivatives