Reactivity of 3-silyloxy-1,4-enynes: Gold(III)-catalyzed regioselective nucleophilic substitution

Gold-catalyzed reactions of 3-silyloxy-1,4-enynes with alcohols afford primary, secondary, and tertiary pent-2-en-4-ynyl ethers in moderate to excellent yields. The substitution proceeds with high regioselectivity. An initial cyclization providing five-membered carbocycles instead was not observed under the reaction conditions. Control experiments show that these reactions are also catalyzed by Bronsted- and Lewis-acids, although scope and yields are markedly reduced. (C) 2008 Elsevier B.V. All rights reserved.