Development of O-Methyl Oxime Benziodoxole-Type Iodine(III) Reagents for Synthesis of 3-Chlorochromone Derivatives.

A stable O-methyl oxime benziodoxole-type iodine(III) reagent was efficiently prepared from o-iodobenzamide derivatives using tert-butyl hypochlorite as oxidant under mild conditions. This new reagent enables an intramolecular cyclization/chlorination of aryl alkynyl ketones, affording a series of 3-chlorochromone derivatives in good to excellent yields. Mechanistic investigations indicate that the reaction proceeds through an ionic pathway involving initial nucleophilic attack, followed by the chloride-mediated demethylation.