Total synthesis and evaluation of (+/-)-N-(tert-butyloxycarbonyl)-CBI, (+/-)-CBI-CDPI1, and (+/-)-CBI-CDPI2 - CC-1065 functional agents incorporating the equivalent 1,2,9,9a-tetrahydrocycloprop 1,2-c benz 1,2-e indol-4-one (CBI) left-hand subunit