Borane/silane frustrated Lewis pairs for polymerization of β-substituted Michael acceptors

TETRAHEDRON

卷:75

Article

McGraw, Michael L.¹  Chen, Eugene Y-X¹ 

[1] Colorado State Univ, Dept Chem, Ft Collins, CO 80523 USA

关键词: Lewis pair polymerization;    Group transfer polymerization;    Frustrated lewis pair;    Hydrosilylation;    Crotonates;   

DOI  :  10.1016/j.tet.2019.02.019

来源: Elsevier

【 摘 要 】

Frustrated Lewis pairs (FLPs) of Lewis acid (LA) B(C6F5)(3) and Lewis base hydrosilane [SiH] have been utilized to promote controlled polymerization of a challenging beta-substituted Michael acceptor, methyl crotonate (MC), devoid of chain transfer side reactions. Mechanistic studies show that chain initiation involves LA-catalyzed 1,4-hydrosilylation of MC with [SiH] via FLP-type activation, generating a silyl ketene acetal nucleophile that participates in chain propagation via classic LA activation of monomer and a bimolecular conjugate addition mechanism. The role of the LA is conflicting in the two different catalytic cycles: the FLP activation in chain initiation requires LA-substrate (monomer) dissociation (or weak interaction) while the classic LA activation in chain propagation demands LA-monomer association (or strong interaction). (C) 2019 Elsevier Ltd. All rights reserved.

【 授权许可】

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