| Abstract
| - Several unsaturated sulfonamides underwent intramolecular aziridination when treated with PhI(OAc)2, MgO, and catalytic Rh2(OAc)4 to give bicyclic aziridines in excellent yield. Treatment ofthe resulting azabicyclic sulfonamides in methanol in the presence of p-TsOH resulted in exclusiveopening of the aziridine ring at the most substituted position affording six- and seven-memberedring products in high yield. In contrast, the intramolecular aziridination of several cycloalkenyl-substituted carbamates did not require a Rh(II) catalyst and proceeded via an iminoiodinaneintermediate. The resulting tricyclic aziridines underwent ring opening when treated with variousnucleophiles to give anti-derived products as expected for nucleophilic attack at the three-memberedring. The iodine(III)-mediated reaction of a 3-indolyl-substituted carbamate, however, required aRh(II) catalyst. The expected aziridine was not observed, but rather simultaneous spirocyclizationof C3 and stereoselective syn-acylation at C2 occurred to give compound 41, whose structure wasunequivocally established by an X-ray crystallographic study. The reaction proceeds in a stepwisemanner via a metal-free zwitterionic intermediate which is attacked by a nucleophilic reagent onthe same side of the amide anion. Related reactions occurred with both a 2-indolyl- and3-benzofuranyl-substituted carbamate but with lower stereoselectivity.
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