Ketyl−Allene Cyclizations Promoted by Samarium(II) Iodide
作者:Gary A. Molander、Elizabeth Pollina Cormier
DOI:10.1021/jo047887s
日期:2005.4.1
Samarium(II) iodide has proven to be an effective reagent for intramolecular reductive coupling reactions. Previous investigations of intramolecular ketyl−olefin coupling reactions provided carbocycles in excellent yield and good diastereoselectivity. This method has been extended to ketyl cyclizations with allenes. Substrates leading to both carbocycles and heterocycles in a selective manner are explored
Irradiation of alpha-iodocycloalkanones bearing an allenyl side chain with a sunlamp effected atom-transfer cyclization to give cyclized products in good yield. A mechanism, involving radical atom-transfer cyclization accompanied by 1,5- and 1,4-hydrogen transfers, is proposed.
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