In this paper, a series of new optically active MeO-BIPHEP-type ligands, （S）-6,6＇-dimethoxy-2,2＇-bis（dip-alkoxyphenyl-phosphine）-l,l＇-biphenyl [（S）-5b-（S）-5e] were prepared and characterized. Starting from ...In this paper, a series of new optically active MeO-BIPHEP-type ligands, （S）-6,6＇-dimethoxy-2,2＇-bis（dip-alkoxyphenyl-phosphine）-l,l＇-biphenyl [（S）-5b-（S）-5e] were prepared and characterized. Starting from the commercially available triethyl phosphorite and m-bromoanisole, an optically active （S）-6,6＇-dimethoxybiphenyl- 2,2＇-diyl-bis（phosphonic acid diester） was prepared by an improved way and converted to the corresponding dichlorides, which was used as a key intermediate to react with p-alkoxybenzenemagnesium bromide or p-alkoxyphenyl lithium to directly give the enantiomerically pure diphosphines 5.展开更多
A new kind of chiral diphosphine PyrPhos-functionalized codendrimers have been synthesized via a liq- uid-phase strategy in high yields. The resulting dendrimeric PyrPhos ligands were purified by a simple solvent pre-...A new kind of chiral diphosphine PyrPhos-functionalized codendrimers have been synthesized via a liq- uid-phase strategy in high yields. The resulting dendrimeric PyrPhos ligands were purified by a simple solvent pre- cipitation without the need for chromatographic separation, and well characterized by 1H, 13C and 31p NMR, MALDI-TOF mass spectroscopy as well as elemental analysis. Their rhodium complexes were applied to the asymmetric hydrogenation of a-acetamido cinnamic acids. Excellent enantioselectivities were achieved, which are comparable to those with the corresponding small molecular catalysts. In addition, these codendrimeric catalysts showed better catalytic performance than the dendrimeric catalysts with Rh（PyrPhos） sites located in the focal point ofpoly（aryl ether） dendrons or in the periphery ofpoly（propyleneimine） dendrimers.展开更多
基金Project supported by the National Natural Science Foundation of China （No. 20272037） and the Doctor＇s Foundation of Education Ministry of China （No. 20030610022）.
文摘In this paper, a series of new optically active MeO-BIPHEP-type ligands, （S）-6,6＇-dimethoxy-2,2＇-bis（dip-alkoxyphenyl-phosphine）-l,l＇-biphenyl [（S）-5b-（S）-5e] were prepared and characterized. Starting from the commercially available triethyl phosphorite and m-bromoanisole, an optically active （S）-6,6＇-dimethoxybiphenyl- 2,2＇-diyl-bis（phosphonic acid diester） was prepared by an improved way and converted to the corresponding dichlorides, which was used as a key intermediate to react with p-alkoxybenzenemagnesium bromide or p-alkoxyphenyl lithium to directly give the enantiomerically pure diphosphines 5.
文摘A new kind of chiral diphosphine PyrPhos-functionalized codendrimers have been synthesized via a liq- uid-phase strategy in high yields. The resulting dendrimeric PyrPhos ligands were purified by a simple solvent pre- cipitation without the need for chromatographic separation, and well characterized by 1H, 13C and 31p NMR, MALDI-TOF mass spectroscopy as well as elemental analysis. Their rhodium complexes were applied to the asymmetric hydrogenation of a-acetamido cinnamic acids. Excellent enantioselectivities were achieved, which are comparable to those with the corresponding small molecular catalysts. In addition, these codendrimeric catalysts showed better catalytic performance than the dendrimeric catalysts with Rh（PyrPhos） sites located in the focal point ofpoly（aryl ether） dendrons or in the periphery ofpoly（propyleneimine） dendrimers.
