Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates.

Takamichi Wakamatsu,Kazunori Nagao,Masaya Sawamura,Hirohisa Ohmiya

doi:10.3762/bjoc.11.265

Abstract

A copper-catalyzed conjugate addition of alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) to alkynoates to form β-disubstituted acrylates is reported. The addition occurred in a formal syn-hydroalkylation mode. The syn stereoselectivity was excellent regardless of the substrate structure. A variety of functional groups were compatible with the conjugate addition.

Highlights

Copper-mediated conjugate additions of organometallic reagents to alkynoates are powerful tools for the synthesis of multisubstituted alkenes [1,2,3,4,5,6,7,8]
Yamamoto and co-workers developed copper-catalyzed conjugate additions of aryl- and allylboron compounds to alkynoates [9,10], but alkylboron compounds have not been used for these methods [11]
As related studies we reported earlier the copper-catalyzed conjugate addition of alkylboranes to imidazole

Summary

Introduction

Copper-mediated conjugate additions of organometallic reagents to alkynoates are powerful tools for the synthesis of multisubstituted alkenes [1,2,3,4,5,6,7,8]. As related studies we reported earlier the copper-catalyzed conjugate addition of alkylboranes (alkyl-9-BBN) to imidazole- We report a copper-catalyzed conjugate addition of alkylboranes to alkynoates, providing a versatile approach to β-disubstituted acrylates [16,17,18,19]. The syn stereoselectivity was excellent regardless of the substrate structure, and a variety of functional groups were tolerated in both the alkylborane and the alkynoate.

Results

Conclusion