Synthesis of Chiral Aromatic Alcohols: Use of New C<sub>2</sub>-Symmetric Rh<sup>III</sup>Cp∗, Ru<sup>II</sup>(cymene), or Ru<sup>II</sup>(benzene) Complexes Containing Chiral Diaminocyclohexane Ligand as Asymmetric Transfer Hydrogenation Catalyst
Abstract Twelve chiral secondary alcohols were synthesized by asymmetrictransferhydrogenation (ATH) using C2-symmetric bis(sulfonamide) ligand (2) derived from (1R,2R)-cyclohexane-1,2-diamine and complexed with [RhCl2Cp*]2, [RuCl2(cymene)]2, or [RuCl2(benzene)]2 and then used in situ in the reduction of prochiral ketones. The alcohols were obtained in 85–99% yield and 90–99% enantioselectivity with
Ionic liquids for enhancing the enantioselectivity of isolated BVMO-catalysed oxidations
作者:Cristina Rodríguez、Gonzalo de Gonzalo、Marco W. Fraaije、Vicente Gotor
DOI:10.1039/c0gc00560f
日期:——
The present study describes the first-time usage of an isolated thermostable Baeyer–Villiger monooxygenase (phenylacetone monooxygenase, PAMO) in the presence of ionic liquids. The stability, activity and selectivity of PAMO as an oxidative enzyme in the presence of different ionic liquids were studied. This revealed that the addition of some specific ionic liquids, such Ammoeng™ 102 and [bmim]MeSO4, can significantly enhance the E-value in the oxidation of racemic benzylketones. Moreover, the use of ionic liquids increases the optimal substrate concentration for performing Baeyer–Villiger oxidation, thereby extending the biocatalytic repertoire of PAMO for synthetic applications.
Mechanochemical Enzymatic Kinetic Resolution of Secondary Alcohols under Ball-Milling Conditions
作者:José G. Hernández、Marcus Frings、Carsten Bolm
DOI:10.1002/cctc.201600455
日期:2016.5.20
Surprisingly, mechanochemical enzymatic transformations have only scarcely been studied until now. Here, we demonstrate the use of lipase B from Candida antarctica (CALB) in acylative kineticresolutions of secondaryalcohols in mixer and planetary mills. Despite the mechanical stress caused by the high‐speed ball milling, the biocatalyst proved highly effective, stable, and, in part, recyclable under the
One-pot kinetic resolution–Mitsunobu reaction to access optically pure compounds, using silver salts in the substitution protocol
作者:Hiten B. Raval、Ashutosh V. Bedekar
DOI:10.1039/d0nj04802j
日期:——
Racemic carbinols were converted to chirally pure acetates by a combination of one-pot, enzyme mediated KR and Mitsunobu reaction with metal acetates. Use of AoNO3 or mixture with NaOAc gave excellent results. The protocol is further extended to introduce azide in place of acetate.
A general and practical process for the conversion of prochiral ketones into the corresponding chiral acetates has been realized. An iron carbonyl complex is reported to catalyze the hydrogenation–dehydrogenation–hydrogenation of prochiral ketones. By merging the iron‐catalyzed redox reactions with enantioselective enzymatic acylations a wide range of benzylic, aliphatic and (hetero)aromatic ketones