Pd-catalyzed regioselective acylation of α,β-unsaturated ketone derivatives by acylzirconocene chloride as an acyl group donor
作者:Yuji Hanzawa、Nobuhito Tabuchi、Kensuke Narita、Akito Kakuuchi、Masaya Yabe、Takeo Taguchi
DOI:10.1016/s0040-4020(02)00857-8
日期:2002.9
reacted with acylzirconocene chloride to give regioselectively 1,4-products under the Pd-catalyzed conditions. In contrast to the reactions of α,β-enones, the presence of a triphenylphosphine ligand brought about the selective formation of 1,4-adduct. By virtue of the phosphine ligand-effect in the addition of an acyl anion to α,β-enones, enantioselective 1,2-addition of acylzirconocene chloride to cyclic
酰基锆茂金属氯化物与α,β-不饱和酮(α,β-烯酮或-炔酮)反应,在Pd催化条件下产生区域选择性的1,2-或1,4-产物。在α,β-烯酮的反应中,通过选择Pd(II)催化剂体系可获得极好的区域选择性。因此,通过选择PdCl 2(PPh 3)2或Pd(OAc)2 -BF 3 ·OEt 2选择性地制备1,2-或1,4-产物。, 分别。单齿膦配体的存在选择性地产生1,2-加成产物。在这些Pd催化的反应中,Pd(0)被认为是一种活性催化剂,它是通过将酰基从锆过渡到Pd(II)原位生成,然后还原性消除Pd(0)而生成的。在Pd催化的条件下,α,β-壬烯还与酰基锆茂金属反应生成区域选择性的1,4-产物。与α,β-烯酮的反应相反,三苯基膦配体的存在导致1,4-加合物的选择性形成。通过在α,β-烯酮中添加酰基阴离子的膦配体效应,在适度的光学纯度(〜66%ee)下进行酰基锆茂金属氯化物与环状α,β-烯酮的对映选择性1