Issue 4, 2018

Cobalt-catalyzed regioselective stereoconvergent Markovnikov 1,2-hydrosilylation of conjugated dienes

Abstract

We report the first stereoconvergent Markovnikov 1,2-hydrosilylation of conjugated dienes using catalysts generated from bench-stable Co(acac)2 and phosphine ligands. A wide range of E/Z-dienes underwent this Markovnikov 1,2-hydrosilylation in a stereoconvergent manner, affording (E)-allylsilanes in high isolated yields with high stereoselectivities (E/Z = >99 : 1) and high regioselectivities (b/l up to > 99 : 1). Mechanistic studies revealed that this stereoconvergence stems from a σ–π–σ isomerization of an allylcobalt species generated by the 1,4-hydrometalation of Z-dienes. In addition, a cobalt catalyst that can only catalyze the hydrosilylation of the E-isomer of an (E/Z)-diene was identified, which allows the separation of the (Z)-isomer from an isomeric mixture of (E/Z)-dienes. Furthermore, asymmetric hydrosilylation of (E)-1-aryl-1,3-dienes was studied with Co(acac)2/(R)-difluorphos and good enantioselectivities (er up to 90 : 10) were obtained.

Graphical abstract: Cobalt-catalyzed regioselective stereoconvergent Markovnikov 1,2-hydrosilylation of conjugated dienes

Supplementary files

Article information

Article type
Edge Article
Submitted
12 Sep 2017
Accepted
26 Nov 2017
First published
27 Nov 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2018,9, 973-978

Cobalt-catalyzed regioselective stereoconvergent Markovnikov 1,2-hydrosilylation of conjugated dienes

H. L. Sang, S. Yu and S. Ge, Chem. Sci., 2018, 9, 973 DOI: 10.1039/C7SC04002D

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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