Lewis Acid‐Catalyzed Diastereoselective C−C Bond Insertion of Diazo Esters into Secondary Benzylic Halides for the Synthesis of α,β‐Diaryl‐β‐haloesters

Abstract

We report a formal carbon–carbon (C−C) bond insertion via the reaction of secondary benzylic halides (fluorides, chlorides, and bromides) with α‐diazo esters catalyzed by Lewis acid catalysts. Secondary benzylic halides underwent elongation to afford α,β‐diaryl‐β‐haloesters diastereoselectively. Density functional theory calculation revealed that the present formal C−C bond insertion was the result of Lewis acid‐promoted cleavage and the re‐formation of a carbon–halogen bond and that the aryl‐migration step determined the diastereoselectivity. Various diarylmethyl halides and α‐diazo esters were applicable to this reaction system. In addition, ring expansion in cyclic benzylic chlorides was accomplished.