Stereochemical aspects of the iodine(III)-mediated aziridination reaction of some cyclic allylic carbamates.

[reaction: see text] The iodine(III)-mediated aziridination reaction of an indolyl-substituted carbamate requires a Rh(II) catalyst and proceeds by a metallonitrene intermediate. Stepwise addition across the indole pi-bond followed by Rh(II) detachment generates a metal-free zwitterion, which ultimately leads to the observed products. In contrast, intramolecular aziridination of several cycloalkenyl carbamates does not require a Rh(II) catalyst and occurs via an iminoiodinane intermediate.