Abstract
cis-9b-Cyano-3a-methyl-2, 3, 3a, 4, 5, 9b-hexahydro-1H-benz [e] indene derivatives (14, 20) were synthesized stereoselectively via the intramolecular Diels-Alder reaction of 1, 2-dihydrobenzocyclobutenes (11, 19). The cis stereochemistry in the cycloadducts was confirmed by nuclear Overhauser effect (NOE) experiments. Examination of CPK molecular models revealed that the stereoselectivity of the transformations could be attributed to a predominance of the endo conformer (e.g. 12) in the transition state. Moreover, the stereochemical outcome of the decyanation of 14 by dissolving metal reduction is also considered.
