posted on 2003-06-17, 00:00authored byJay P. Parrish, David B. Kastrinsky, Dale L. Boger
An efficient eight-step synthesis (54% overall) and the subsequent X-ray characterization of 1,2,9,9a-tetrahydrocyclopropa[c]benz[e]-3-azaindol-4-one (CBA) containing an aza variant of the CC-1065/duocarmycin alkylation subunit are detailed. Despite the unique deep-seated aza modification
providing an unprecedented and stable 2-aza-4,4-spirocyclopropacyclohexadienone, CBA proved to be structurally identical with CBI, the
carbon analogue, in terms of the stereoelectronic alignment of the key cyclopropane, its bond lengths, and the length of the diagnostic
C3a−N2 bond reflecting the extent of vinylogous amide conjugation.