title: Synthesis of (+/-)-Gymnomitrol. Mn(OAc)(3)-Initiated Free-Radical Cyclization of Alkynyl Ketones.
abstract: Mn(OAc)(3)-initiated cyclization of alkynyl ketones in 9-19:1 EtOH/HOAc at 90 degrees C is a useful cyclization procedure in favorable cases. Cyclization of (trimethylsilyl)alkynyl ketone 4e provides 62% of silylalkenes 26 and 27 in the key reaction of a seven-step (16% overall yield) synthesis of gymnomitrol (1) from readily available ketone 23. 9alpha-Hydroxygymnomitryl acetate (2) and 9-oxogymnomitryl acetate (3) have been prepared from gymnomitrol. Cyclization of propargyl cyclohexanones 39a-c provides bicyclic compounds 40-42 in 40-60% yield.
authors.affiliation: Department of Chemistry, Brandeis University, Waltham, Massachusetts 02254-9110.
authors.forename: Steven V.
authors.initials: SV
authors.lastname: O'Neil
authors.forename: Cheri A.
authors.initials: CA
authors.lastname: Quickley
authors.forename: Barry B.
authors.initials: BB
authors.lastname: Snider