Derivatives of Methyl 5-Methyl-4-oxo-1,2,4,5,8,8a-hexahydrocyclopropa[3]pyrrolo[3,2-e]indole-3-carboxylate: A Case of Inverse Electronic Effects on the Reactivity of CC-1065 Derivatives[J. Am. Chem. Soc.2001,123(21), 5102−5103].