Engaging unactivated alkyl, alkenyl and aryl iodides in visible-light-mediated free radical reactions.

Autor: Nguyen JD; Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA., D'Amato EM, Narayanam JM, Stephenson CR
Jazyk: angličtina
Zdroj: Nature chemistry [Nat Chem] 2012 Oct; Vol. 4 (10), pp. 854-9.
DOI: 10.1038/nchem.1452
Abstrakt: Radical reactions are a powerful class of chemical transformations. However, the formation of radical species to initiate these reactions has often required the use of stoichiometric amounts of toxic reagents, such as tributyltin hydride. Recently, the use of visible-light-mediated photoredox catalysis to generate radical species has become popular, but the scope of these radical precursors has been limited. Here, we describe the identification of reaction conditions under which photocatalysts such as fac-Ir(ppy)3 can be utilized to form radicals from unactivated alkyl, alkenyl and aryl iodides. The generated radicals undergo reduction via hydrogen atom abstraction or reductive cyclization. The reaction protocol utilizes only inexpensive reagents, occurs under mild reaction conditions, and shows exceptional functional group tolerance. Reaction efficiency is maintained upon scale-up and decreased catalyst loading, and the reaction time can be significantly shortened when the reaction is performed in a flow reactor.
Databáze: MEDLINE