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Light‐Driven Vitamin B 12 ‐Catalysed Generation of Acyl Radicals from 2‐ S ‐Pyridyl Thioesters
Author(s) -
Ociepa Michał,
Baka Oskar,
Narodowiec Jakub,
Gryko Dorota
Publication year - 2017
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201700913
Subject(s) - chemistry , radical , acylation , photodissociation , combinatorial chemistry , catalysis , substrate (aquarium) , functional group , derivative (finance) , organic synthesis , photochemistry , organic chemistry , oceanography , polymer , financial economics , economics , geology
Acyl radicals are invaluable intermediates in organic synthesis, however their generation remains challenging. Herein, we present an unprecedented light‐driven, cobalt‐catalysed method for the generation of acyl radicals from readily available 2‐ S ‐pyridyl thioesters. The synthetic potential of this methodology was demonstrated in the Giese‐type acylation of activated olefins in the presence of heptamethyl cobyrrinate. This vitamin B 12 derivative proved to be the most efficient catalyst in the studied process. The developed method features broad substrate scope (38 examples), good functional group tolerance, and mild reaction conditions. Moreover, it is easily scalable (illustrated on a 20‐fold scale‐up procedure), enabling its preparative use. Mechanistic studies revealed that the reaction proceeds via a radical pathway with the key steps involving the formation of an acyl‐vitamin B 12 complex and subsequent photolysis of the Co−C bond.