Bismuth‐Mediated α‐Arylation of Acidic Diketones with ortho‐Substituted Boronic Acids

Abstract

The α-arylation of cyclic and fluoroalkyl 1,3diketones is made challenging by the highly stabilized nature of the corresponding enolates, and is especially difficult for sterically demanding aryl partners. As a general solution to this problem, we report the Bimediated oxidative coupling of acidic diones and orthosubstituted arylboronic acids. Starting from a benchstable bismacycle precursor, a sequence of B-to-Bi transmetallation, oxidation and CÀ C bond formation furnishes the arylated diones. Development of methodology that tolerates both sensitive functionality and steric demand is supported by interrogation of key reactive intermediates. Application of our strategy to cyclic diones enables the concise synthesis of important agrochemical intermediates which were previously prepared using toxic Pb reagents. This methodology also enables the first ever arylation of fluoroalkyl diones which, upon condensation with hydrazine, provides direct access to valuable fluoroalkyl pyrazoles.

Recent advances in palladium‐catalyzed α‐arylation reactions

“…It enables the synthesis of important compounds with desirable properties that are significant in various disciplines. α‐Arylated compounds are basic constituents of wide range of agrochemicals 1 and pharmaceuticals 2–4 …”