Selective Synthesis of Organoboron Compounds with Copper(I)-Phosphine Complex Catalysts

Transition-metal-catalyzed borylation has emerged as a powerful method for preparation of organoboron compounds, which are useful synthetic reagents in organic synthesis. However, chemo-, regio-, and stereoselective synthesis of the boron compounds are still highly required.Herein, we report copper(I)-catalyzed boryl substitution of allylic carbonates and ethers, monoborylation of 1,3-dienes and enynes, boryl substitution of alkyl halides, and borylative cyclization of alkenes containing an appropriate leaving group for the selective synthesis of various organoboron compounds including allyl- and allenylboronates, and optically active carbocyclic boronates. Preparation of the borylation products has been difficult with known procedures. In addition, direct enantio-convergent transformation of racemic substrates without a racemization or symmetrization process, a novel methodology for asymmetric synthesis with racemic substrates, is also reported.