官能化二硫缩烯酮的选择性α-溴代反应

Selective α-Bromination of Functionalized Ketene Dithioacetals

发展了一种适用范围广、高效且高选择性的官能化二硫缩烯酮的α-溴代反应.在少量水存在下,在四氢呋喃溶液中,以溴化铜为溴代试剂,经由官能化二硫缩烯酮(1)的α-溴代反应制备了结构多样的α-溴代二硫缩烯酮(2).

Functionalized ketene dithioacetals are important intermediates in organic synthesis.α-Functionalization reactions based on them provide potential precursors for the construction of usefully carbo-and heterocyclic compounds.In this paper,a versatileα-bromination of functionalized ketene dithioacetals was developed.In the presence of H2 O,the reactions of functionalized ketene dithioacetals（1） with CuBr 2 in THF at room temperature gave variousα-bromo ketene dithioacetals（2） in excellent yields with high regioselectivities.The mechanism of thisα-bromination is proposed to undergo an addition of bromine formed in situ to compound 1 and sequontial elimination of theα-proton.The simplicity of execution,mild conditions,inexpensive,easily usable brominating agent and high yields,make this synthetic method attractive for practical applications.