Preparation of Optically Active 2,2'‐Dibromo‐6,6'‐diiodo‐1,1'‐biphenyl: A Powerful Precursor for Modular Synthesis of Functionalized Atropisomers†

Abstract

Comprehensive SummaryThe widespread applications of atropisomeric compounds have led to an increasing demand for their synthesis. Rather than synthesizing different functionalized atropisomers individually, an attractive alternative is to identify a key intermediate or precursor that can be readily elaborated and functionalized to realize divergent synthesis of this class of compounds. Building on our previous research on asymmetric ring‐opening of cyclic diaryliodoniums, in this work we developed a copper‐catalyzed enantioselective ring‐opening reaction of ortho,ortho’‐dibromo substituted cyclic diaryliodonium with lithium iodide. The resulting optically active product 2,2'‐dibromo‐6,6'‐diiodo‐1,1'‐biphenyl, possessing two C—Br bonds and two C—I bonds, can be selectively advanced to form different functionalities. Remarkably, the utilities of the product were highlighted by successively demonstrating C—I and C—Br metalation, followed by carboxylation, boroylation, oxygenation, allylation, phosphinylation, etc., all of which provide a new and convenient approach to synthesizing a range of functionalized axially chiral biphenyls.