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Regioselective Simmons–Smith-type cyclopropanations of polyalkenes enabled by transition metal catalysis

A [(i–Pr)PDI]CoBr(2) complex (PDI = pyridine-diimine) catalyzes Simmons–Smith-type reductive cyclopropanation reactions using CH(2)Br(2) in combination with Zn. In contrast to its non-catalytic variant, the cobalt-catalyzed cyclopropanation is capable of discriminating between alkenes of similar ele...

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Detalles Bibliográficos
Autores principales: Werth, Jacob, Uyeda, Christopher
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5890799/
https://www.ncbi.nlm.nih.gov/pubmed/29675205
http://dx.doi.org/10.1039/c7sc04861k
Descripción
Sumario:A [(i–Pr)PDI]CoBr(2) complex (PDI = pyridine-diimine) catalyzes Simmons–Smith-type reductive cyclopropanation reactions using CH(2)Br(2) in combination with Zn. In contrast to its non-catalytic variant, the cobalt-catalyzed cyclopropanation is capable of discriminating between alkenes of similar electronic properties based on their substitution patterns: monosubstituted > 1,1-disubstituted > (Z)-1,2-disubstituted > (E)-1,2-disubstituted > trisubstituted. This property enables synthetically useful yields to be achieved for the monocyclopropanation of polyalkene substrates, including terpene derivatives and conjugated 1,3-dienes. Mechanistic studies implicate a carbenoid species containing both Co and Zn as the catalytically relevant methylene transfer agent.