Development and Mechanistic Investigation of a Highly Efficient Iridium(V) Silyl Complex for the Reduction of Tertiary Amides to Amines
作者:Sehoon Park、Maurice Brookhart
DOI:10.1021/ja209567m
日期:2012.1.11
quantitatively reduced to tertiary amines under mild conditions with low catalyst loading. A detailed mechanistic study has been carried out and intermediates identified. In brief, (POCOP)IrH(3)(SiEt(2)H) reduces the amide to the hemiaminal silyl ether that, in the presence of a trialkylammonium salt, is ionized to the iminium ion, which is then reduced to the tertiary amine by Et(2)SiH(2). Good functional
阳离子 Ir(III) 丙酮络合物 (POCOP)Ir(H)(2)(丙酮)(+)(POCOP = 2,6-双(二叔丁基膦)苯基)被证明可以催化多种使用二乙基硅烷作为还原剂将叔酰胺转化为胺。机理研究确定,在反应中生成的次要物种,中性三氢化硅烷 Ir(V) 复合物 (POCOP)IrH(3)(SiEt(2)H),是催化活性物种。在 H(2) 下 Et(2)SiH(2) 存在下,用叔丁醇处理现成的 (POCOP)IrHCl 可以方便地生成高浓度的这种物质。因此,在三烷基铵盐的存在下使用该混合物,在温和条件下以低催化剂负载量将多种叔酰胺(包括极其庞大的底物)快速且定量地还原为叔胺。已经进行了详细的机理研究并确定了中间体。简而言之,(POCOP)IrH(3)(SiEt(2)H) 将酰胺还原为半氨基甲硅烷基醚,在三烷基铵盐的存在下,该醚被电离为亚胺离子,然后将其还原为叔胺通过 Et(2)SiH(2)。