Asymmetric Reactions Catalyzed by Chiral Metal Complexes. LVII. Synthesis of Efficient Chiral Bisphosphine Ligands, Modified DIOPs, (4R,5R)-4-(Diaryl- or dialkylphosphino)methyl-5-(diarylphosphino)methyl-2,2-dimethyl-1,3-dioxolanes, and Their Use in Rhodium(I)-Catalyzed Asymmetric Hydrogenations.
作者:Toshiaki MORIMOTO、Mitsuo CHIBA、Kazuo ACHIWA
DOI:10.1248/cpb.41.1149
日期:——
Modified DIOPs, (4R, 5R)-4-(diaryl- or dialkylphosphino)methyl-5-(diarylphosphino)methyl-2, 2-dimethyl-1, 3-dioxolanes, were prepared on the basis of our design concept, and used as ligands for the rhodium(I)-catalyzed asymmetric hydrogenations of ketopantolactone, itaconic acid, demethyl itaconate, and β-aryl-substituted itaconic acid derivatives. A neutral rhodium(I)-complex of (4R-trans)-dicyclohexyl[[5-[(diphenylphosphino)methyl]-2, 2-dimethyl-1, 3-dioxolan-4-yl]methyl]phosphine (DIOCP) bearing both a dicyclohexylphosphino group and a diphenylphosphino group was found to be a more efficient catalyst than the original DIOP in the asymmetric hydrogenation of ketopantolactone. Modified DIOPs bearing electron-donating groups at their para positions were efficient ligands for the rhodium(I)-catalyzed asymmetric hydrogenations of itaconic acid and its derivatives; in particular, (4R-trans)-[(2, 2-dimethyl-1, 3-dioxolane-4, 5-diyl)bis(metylene)]bis[bis(4'-methoxy-3', 5'-dimethylphenyl)phosphine] (MOD-DIOP) bearing both a p-methoxy group and two m, m'-methyl groups on each phenyl group showed much higher enantioselectivity and catalytic activity than DIOP.
改良的DIOPs,(4R, 5R)-4-(二芳基或二烷基磷酰基)甲基-5-(二芳基磷酰基)甲基-2, 2-二甲基-1, 3-二噁烷,基于我们的设计概念制备,并用作铑(I)催化的酮平滑酸、丁烯二酸、去甲基丁烯二酸酯和β-芳基取代丁烯二酸衍生物的不对称氢化的配体。含有二环己基磷酰基和二苯基磷酰基的(4R-trans)-二环己基[[5-[(二苯基磷酰基)甲基]-2, 2-二甲基-1, 3-二噁烷-4-基]甲基]磷酸盐(DIOCP)被发现是比原始DIOP在酮平滑酸的不对称氢化反应中更有效的催化剂。具有电子给体基团的改良DIOPs在其对位上是铑(I)催化的丁烯二酸及其衍生物不对称氢化的有效配体;特别是,(4R-trans)-[(2, 2-二甲基-1, 3-二噁烷-4, 5-双基)双(亚甲基)]双[双(4'-甲氧基-3', 5'-二甲基苯)磷](MOD-DIOP)同时具有p-甲氧基基团和每个苯基上的两个m, m'-甲基基团,其对映选择性和催化活性显著高于DIOP。