An efficient and environmentally benign protocol for the synthesis of vicinal chlorohydroxy and chloromethoxy derivatives in a highly regioselective manner fromolefins using NH4Cl as a chlorine source and oxone as an oxidant in aqueous acetone and methanol is demonstrated. This methodology offers an additive and metal chloride free approach and is endowed with simple reaction conditions, high yields
Iridium‐catalyzedasymmetrichydrogenation of prochiral halogenated ketones was successfully developed to prepare various chiral halohydrins with high reactivities and excellent enantioselectivities under basic reaction condition (up to >99% conversion, 99% yield, >99% ee). Moreover, gram‐scale experiment was performed well in the presence of just 0.005 mol% (S/C=20 000) Ir/f‐amphox catalyst with 99%
Enantioselective Synthesis of Vicinal Halohydrins via Dynamic Kinetic Resolution
作者:Abel Ros、Antonio Magriz、Hansjörg Dietrich、Rosario Fernández、Eleuterio Alvarez、José M. Lassaletta
DOI:10.1021/ol052821k
日期:2006.1.1
[reaction: see text] Expanding the scope of enantioselective catalysis via DKR, transfer hydrogenation of a variety of cyclic alpha-halo ketones was accomplished using the Noyori/Ikariya (R,R)- or (S,S)-I catalysts and either HCO(2)H/Et(3)N or HCO(2)Na/n-Bu(4)NBr in H(2)O/CH(2)Cl(2) as the hydrogen sources. Good yields of vicinal bromo-, chloro-, and fluorohydrins with excellent de and ee levels were
Convincing Catalytic Performance of Oxo-Tethered Ruthenium Complexes for Asymmetric Transfer Hydrogenation of Cyclic α-Halogenated Ketones through Dynamic Kinetic Resolution
A highly efficient dynamic kinetic resolution of cyclic halohydrins was achieved by the asymmetric transfer hydrogenation of racemic α-haloketones. Bifunctional oxo-tethered Ru(II) catalysts could promote the reduction without deterioration of halogens. By structural tuning of the catalyst, chiral alcohols having halogen, ester, carboxamide, and sulfone functions were obtained variably with excellent
Chemoenzymatic synthesis of enantiopure hydroxy sulfoxides derived from substituted arenes
作者:Derek R. Boyd、Narain D. Sharma、John F. Malone、Vera Ljubez、Deirdre Murphy、Steven D. Shepherd、Christopher C. R. Allen
DOI:10.1039/c5ob02411k
日期:——
Enantiopure β-hydroxy sulfoxides and catechol sulfoxides were obtained, by chemoenzymatic synthesis, involving dioxygenase-catalysed benzylic hydroxylation or arene cis-dihydroxylation and cis-diol dehydrogenase-catalysed dehydrogenation. Absolute configurations of chiral hydroxy sulfoxides were determined by X-ray crystallography, ECD spectroscopy and stereochemical correlation. The application of