Efficient Synthesis of Epoxides from Vicinal Diols Via Cyclic Sulfates
摘要:
Reaction of cyclic sulfates of vic-diols with sodium hydroxide in THF-MeOH produced the corresponding epoxides in excellent isolated yields at room temperature. Cyclic sulfates of trans-diols gave cis-epoxides, and cyclic sulfates of cis-diols afforded trans-epoxides exclusively. Various cyclic sulfates of vic-diols can be converted into the epoxides under the conditions.
Chiral Rhodium Complexes Derived From Electron-Rich Phosphine-Phosphites as Asymmetric Hydrogenation Catalysts
作者:Pablo Etayo、José L. Núñez-Rico、Anton Vidal-Ferran
DOI:10.1021/om200933b
日期:2011.12.26
Two new chiral cationic rhodium(I) complexes derived from electron-rich dicyclohexylphosphine-phosphite ligands were prepared from enantiopure Sharpless epoxy ethers. The best-performing catalyst system, which bears a less bulky methyl ether moiety, exhibited remarkably high enantioselectivity (up to 99% ee) and reactivity (up to >2500 TON) in asymmetric hydrogenation reactions of various functionalized