Synthesis and X-ray analysis of an unprecedented and stable 2-aza-4,4-spirocyclopropacyclohexadienone.
[structure: see text] 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.
Parrish
Jay P
JP
Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Kastrinsky
David B
DB
Boger
Dale L
DL
D018360:Crystallography, X-Ray; D003510:Cyclohexanes / Q000138:chemical synthesis / Q000737:chemistry*; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry*
C478992:2-aza-4,4-spirocyclopropacyclohexadienone; D003510:Cyclohexanes; D013141:Spiro Compounds