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Photocontrolled Cobalt Catalysis for Selective Hydroboration of α,β‐Unsaturated Ketones
Author(s) -
Beltran Frédéric,
Bergamaschi Enrico,
FunesArdoiz Ignacio,
Teskey Christopher J.
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202009893
Subject(s) - hydroboration , chemistry , selectivity , aldol reaction , catalysis , stereoselectivity , substrate (aquarium) , reagent , regioselectivity , nucleophile , combinatorial chemistry , ketone , organic chemistry , oceanography , geology
Selectivity between 1,2 and 1,4 addition of a nucleophile to an α,β‐unsaturated carbonyl compound has classically been modified by the addition of stoichiometric additives to the substrate or reagent to increase their “hard” or “soft” character. Here, we demonstrate a conceptually distinct approach that instead relies on controlling the coordination sphere of a catalyst with visible light. In this way, we bias the reaction down two divergent pathways, giving contrasting products in the catalytic hydroboration of α,β‐unsaturated ketones. This includes direct access to previously elusive cyclic enolborates, via 1,4‐selective hydroboration, providing a straightforward and stereoselective route to rare syn‐aldol products in one‐pot. DFT calculations and mechanistic experiments confirm two different mechanisms are operative, underpinning this unusual photocontrolled selectivity switch.