Manganese (III)-based oxidative free-radical cyclization of unsaturated. beta.-keto esters, 1, 3-diketones, and malonate diesters

SA Kates, MA Dombroski, BB Snider

Index: Kates, Steven A.; Dombroski, Mark A.; Snider, Barry B. Journal of Organic Chemistry, 1990 , vol. 55, # 8 p. 2427 - 2436

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Citation Number: 76

Abstract

Oxidative free-radical cyclizations of unsaturated p-keto esters, 1, 3-diketones, and malonate diesters with 2 equiv of M~(OAC)~.~ H, O and 1 equiv of CU (OAC)~. H~ O are described. Oxidation of@-keto ester 1 with Mn (II1) to enol radical 2 followed by 6-ex0 cyclization gives radical 4, which is oxidized by Cu (I1) to give alkene 7 in 64-71% yield. Oxidation of 9 gives a lower yield of 5-exo cyclization product 11 due to competing overoxidation to give 13. ...