| Abstract
| - An efficient eight-step synthesis (53% overall) and the evaluation of 1,2,9,9a-tetrahydrocyclopropa[c]benz[e]-3-azaindol-4-one (CBA) and its derivatives containing an aza variant of the CC-1065/duocarmycin alkylation subunit are detailed. This unique deep-seated aza modification providedan unprecedented 2-aza-4,4-spirocyclopropacyclohexadienone that was characterized chemicallyand structurally (X-ray). CBA proved structurally identical with CBI, the carbon analogue, includingthe stereoelectronic alignment of the key cyclopropane, its bond lengths, and the bond length ofthe diagnostic C3a−N2 bond, reflecting the extent of vinylogous amide (amidine) conjugation.Despite these structural similarities, CBA and its derivatives were found to be much more reactivetoward solvolysis and hydrolysis, much less effective DNA alkylating agents (1000-fold), andbiologically much less potent (100- to 1000-fold) than the corresponding CBI derivatives.
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