Additions of Chlorosulfonyl Isocyanate to 6‐Substituted Benzonorbornadienes

Abstract

AbstractThe addition of chlorosulfonyl isocyanate (CSI) to 6‐substituted benzonorbornadienes gives pairs of isomeric syn and anti β‐lactam products. Previously published molecular orbital calculations indicate that the benzonorbornadiene π‐bond is not polarized. Relative rate data are inconsistent with either a concerted addition process or a process which proceeds by the direct formation of a carbenium ion intermediate. A mechanism proceeding through the initial formation of a benzonorbornadiene‐CSI π‐complex which decays to a carbenium ion in a product determining step is suggested.