Nickel-catalyzed enantioselective 1,2-vinylboration of styrenes.

Yang Ye,Songwei Jiang,Tian Xie,Xiang-Yang Ye,Jiandong Liu,Renren Bai,Bing Xu,Shijun Li

doi:10.1039/d1sc04071e

Yang Ye, Songwei Jiang + Show 6 more

Open Access

https://doi.org/10.1039/d1sc04071e

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Journal: Chemical Science	Publication Date: Jan 1, 2021
Citations: 17	License type: CC BY 3.0

Affiliation: Hangzhou Normal University, Shanghai University

Abstract

A novel nickel-catalyzed asymmetric 1,2-vinylboration reaction has been developed to afford benzylic alkenylboration products with high yields and excellent enantioselectivities by using a chiral bisoxazoline ligand. Under optimized conditions, a wide variety of chiral 2-boryl-1,1-arylvinylalkanes are efficiently prepared from readily available olefins and vinyl halides in the presence of bis(pinacolato)diboron as the boron source in a mild and easy-to-operate manner. This three-component cascade protocol furnishes exceptional chemo- and stereoselectivity, and its usefulness is illustrated by its application in asymmetric modifications of several structurally complex natural products and pharmaceuticals.

Highlights

Difunctionalization of alkenes through a transition-metal catalyzed process has gradually evolved as a signi cant opportunity for establishing two newly formed stereocenters in a single step, allowing rapid access to molecular complexity.[1]
We initiated our investigation by exploring the enantioselective vinylboration of styrene (1) with (E)-(2-bromovinyl)benzene (2) and bis(pinacolato)diboron (B2pin2) as model substrates using chiral bis(oxazoline) ligands (Table 1)
An extensive screening of the reaction parameters revealed that the use of NiBr2$DME (10 mol%), L1 (10 mol%), and B2pin[2] (1.2 equiv.) as the boron source and LiOMe (1.5 equiv.) as the base in 1,4-dioxane at 10 C delivered compound 3 in 85% yield and 94% ee

Summary

Introduction

Difunctionalization of alkenes through a transition-metal catalyzed process has gradually evolved as a signi cant opportunity for establishing two newly formed stereocenters in a single step, allowing rapid access to molecular complexity.[1]. A novel nickel-catalyzed asymmetric 1,2-vinylboration reaction has been developed to afford benzylic alkenylboration products with high yields and excellent enantioselectivities by using a chiral bisoxazoline ligand. A wide variety of chiral 2-boryl-1,1-arylvinylalkanes are efficiently prepared from readily available olefins and vinyl halides in the presence of bis(pinacolato)diboron as the boron source in a mild and easy-to-operate manner.

Results

Conclusion