Regioselective .epsilon.-alkylation of 5-acetoxy-1,3-alkadienes by organocopper-magnesium reagents
作者:Naoaki Nakanishi、Seijiro Matsubara、Kiitiro Utimoto、Sinpei Kozima、Ryohei Yamaguchi
DOI:10.1021/jo00010a020
日期:1991.5
Treatment of the 5-acetoxy-1,3-alkadienes 1b with dialkylcopper-magnesium complex R2Cu.MgX prepared in tetrahydrofuran gave epsilon-alkylated products, i.e., conjugated (E,E)-alkadienes 2, predominantly. In contrast, when 1b was treated with the alkylcopper-magnesium reagent RCuZ.MgX prepared in diethyl ether, gamma-alkylated 1,4-alkadienes 3 were the major products. The reaction of 6-acetoxy-2,4-tridecadiene (14) with n-BuMeCu.MgBr gave a 52:48 mixture of alpha- and epsilon-butylated products 15 and 16, respectively. The conjugated (E,E)-alkadienes 21 possessing functional groups Y (Y = Br, AcO, Ac, HC = C) at the omega-position were prepared in tetrahydrofuran by the same method.