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Selective Synthesis of Tetrasubstituted Olefins by Copper‐Mediated Acetoxythiolation of Internal Alkynes: Scope and Mechanistic Studies
Author(s) -
Villuendas Pedro,
Ruiz Sara,
Vidossich Pietro,
Lledós Agustí,
Urriolabeitia Esteban P.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201802546
Subject(s) - alkyne , alkene , chemistry , regioselectivity , nucleophile , copper , stereoselectivity , reaction mechanism , combinatorial chemistry , medicinal chemistry , photochemistry , organic chemistry , catalysis
The Cu‐mediated synthesis of tetrasubstituted olefins by the addition of an acetate group and a thiolate to an unactivated internal alkyne is described. The reaction is fully stereoselective, because only the E alkene is obtained. If the alkyne is asymmetric, the reaction also shows a very high degree of regioselectivity. The mechanism of the reaction is elucidated by DFT methods, which show that it takes place through Cu‐stabilized radical species. Calculations highlight the crucial role of the dimeric copper(II) diacetate in the process, as it generates the active species in which the sulfur center has an incipient thiyl radical character and accepting, through a series of changes in the oxidation states of the two copper centers, the two electrons released in the addition of two nucleophiles to the alkyne.