Ortho/Ipso Alkylborylation of Aryl Iodides

Abstract

This work describes a method for the difunctionalization of aryl iodides to generate polysubstituted arenes via Pd catalysis. The reaction hinges on the unique interplay between norbornene and the metal catalyst to impart a guided ortho C–H alkylation event followed by a programmatic ipso borylation to provide a diverse array of substituted arene products. The utility of this transformation is demonstrated through the functionalization of the boronic ester to a variety of valuable functionalities.

Installing the “magic methyl” – C–H methylation in synthesis

“…In a separate study, a complementary Catellani-type ortho methylation/ipso borylation strategy was demonstrated by Smith, where methyl iodide was employed to enable the C(sp 2 )-H methylation/borylation of 2-iodotoluene in 60% yield. 94 The methodology reported by Zhou (vide supra) was also successfully performed on several aryl bromides, an uncommon but synthetically useful development. Dong similarly conducted a Catellani-type C(sp 2 )-H methylation of 2-bromoanisole, in which methyl 4-nitrobenzenesulfonate (MeONs) was utilised as the methylating agent (Scheme 30).…”