Chirally functionalized mesoporous organosilicas with built-in BINAP ligand for asymmetric catalysis
作者:Peiyuan Wang、Xiao Liu、Jie Yang、Yan Yang、Lei Zhang、Qihua Yang、Can Li
DOI:10.1039/b913808k
日期:——
The chirally functionalized periodic mesoporous organosilica (PMO) with C2-symmetric chiral building blocks, BINAP (2,2′-bis(diphenylphosphino)-1,1′-binaphthyl), in the pore wall was successfully synthesized for the first time using a successive co-condensation and post-synthesis modification method. Chiral BINAPO (2,2′-bis(diphenylphosphinooxide)-1,1′-binaphthyl) bridging mesoporous organosilica with highly ordered 2-D hexagonal structure was first synthesized by co-condensation of (R)-5,5′-bis(3-triethoxysilylpropyl-1-ureyl)-2,2′-bis(diphenylphosphinooxide)-1,1′-binaphthy with tetramethoxylsilane in the presence of block copolymer P123 as template under weakly acidic conditions. The BINAPO in the pore wall of PMO was reduced with trichlorosilane to generate BINAP using a post-synthesis modification method. The chiral PMO with built-in BINAP (coordination with [RuCl2-(benzene)]2) is an efficient solid catalyst for the asymmetric hydrogenation of β-keto esters with ee as high as 99%, which is among the highest ever reported for the chirally functionalized PMOs in asymmetric catalysis.
首次成功合成了孔壁中具有C2对称性手性构筑单元BINAP(2,2′-双(二苯基膦)-1,1′-联萘)的手性官能化周期性介孔有机硅(PMO),采用连续共缩聚和后合成修饰方法。通过在弱酸性条件下以嵌段共聚物P123为模板,首次通过(R)-5,5′-双(3-三乙氧基硅丙基-1-脲基)-2,2′-双(二苯基膦氧)-1,1′-联萘与四甲氧基硅烷的共缩聚合成了具有高度有序的二维六方结构的BINAPO(2,2′-双(二苯基膦氧)-1,1′-联萘)桥连介孔有机硅。通过后合成修饰方法,使用三氯硅烷将PMO孔壁中的BINAPO还原生成BINAP。内置BINAP(与[RuCl2-(苯)]2配位)的手性PMO是一种高效的固体催化剂,用于β-酮酯的不对称氢化,其ee值高达99%,这是不对称催化中手性官能化PMO报道的最高值之一。