Titanium(IV) bromide and boron(III) tribromide promoted reactions of arylaldehydes with 3-butyn-2-one, methyl propiolate and propynenitrile
作者:Min Shi、Chun-Jiang Wang
DOI:10.1016/s0040-4020(02)01127-4
日期:2002.10
α-brominated compounds, derived from the reactions of arylaldehydes with methyl propiolate, were obtained in low yields. While, at 70°C in 1,2-dichloroethane, β,β-dibrominated compounds were obtained from the reactions of arylaldehydes with methyl propiolate or propynenitrile in the presence of TiBr4 in moderate yields. The substituent on the phenyl ring can affect the reaction rate and the E/Z ratio. In addition
芳醛与3-丁炔-2-酮,丙炔酸甲酯或propynenitrile在刘易斯的存在下反应,酸如钛(IV),溴化(TiBr 4)或硼(III),三溴化(的BBr 3)(1.4当量)罐受反应温度的影响很大。当芳基醛与3-丁炔-2-酮的反应在<-20℃下进行时,获得了溴化化合物作为主要产物。然而,当反应在室温(20℃)下进行时,溴化化合物和α,β-二溴化化合物均形成为主要产物。另外,在70℃下的1,2-二氯乙烷中,单独得到α,β-二溴代化合物。另一方面,在TiBr存在下芳基醛与丙酸甲酯或丙腈的反应4在室温(20°C)时非常慢。以低收率获得了衍生自芳基醛与丙酸甲酯的反应的相应的α-溴化化合物。而在70°C下的1,2-二氯乙烷中,在TiBr 4存在下,芳基醛与丙酸甲酯或丙腈的反应可制得β,β-二溴化化合物。苯环上的取代基会影响反应速率和E / Z比。另外,在两种底物的情况下,已经研究了钯催化的烯丙基取代和Suzuki型偶联反应。