Abnormal behaviour of 8b,8c,9,11,11a,11b-Hexahydro- and 8c,9,11,11a-Tetrahydro-phenanthro[9',10':3,4]cyclobuta[1,2-c]furan during bromination with N-bromosuccinimide

Abstract

Dimethyl 1,2,2a,10b-tetrahydrocyclobuta[l]phenantene-cis-1,2- dicarboxylate has been converted into 8b,8c,9,11,11a,11b- hexahydrophenanthro[9?,10?:3,4]cyclobuta[1,2-c]furan (9) and 8c,9,11,11a-tetrahydrophenanthro[9?,10?:3,4]cyclobuta[1,2-c]furan (5) by a series of standard reactions. Bromination of (9) with N- bromosuccinimide gave 3-bromo-4-(9?-phenanthryl)tetrahydrofuran (14) by an unusual fragmentation of the cyclobutyl ring. Reaction of (5) with N-bromosuccinimide resulted in the introduction of the N-succinimyl substituents into the α-position of the tetrahydrofuran ring.