在水中由钼(VI)或钨(VI)吡啶醇络合物进行的顺丙烯膦酸的异相催化不对称环氧化

合成了手性吡啶醇二氧合钼(VI)及二氧合钨(VI)配合物, 采用这两种配合物作为催化剂, 实现了在水中对顺丙烯膦酸(CPPA)的催化不对称环氧化. 这两种催化剂不溶于水, 因此, 这是一个发生在固液两相界面上的异相催化不对称环氧化反应. 其中手性吡啶醇二氧合钼在0 ℃下的对映选择性ee值达到71%; 加入相转移催化剂四正丁基溴化铵, 催化剂的活性和对映选择性有显著提高, 其中手性吡啶醇二氧合钨在50 ℃下ee值由54%提高到78%. 手性吡啶醇二氧合钼和二氧合钨催化剂可以回收再使用.

Heterogeneous Asymmetric Epoxidation of cis-1-Propenyl-phosphonic Acid in H2O Catalyzed by Chiral Mo(VI) or W(VI) 2''-Pyridinyl Alcoholate Complex

In this paper, chiral molybdenum(VI) or tungsten(VI) 2'-pyridinyl alcoholate complex catalyzed asymmetric epoxidation of cis-1-propenylphosphonic acid in H₂O was reported. This is an asymmetric epoxidation reaction taking place on the solid-liquid interface. The highest ee value of 71% was achieved by using chiral molybdenum(VI) 2'-pyridingyl alcoholate complex at 0 ℃. After addition of phase transfer catalyst Bu₄NBr, the yield and ee value were remarkably increased. For example, using chiral tungsten(VI) 2'-pyridinyl alcoholate complex at 50 ℃, the ee value was increased from 54% to 78%.