Transfer Hydrogenation in Water: Enantioselective, Catalytic Reduction of α-Cyano and α-Nitro Substituted Acetophenones
作者:Omid Soltani、Martin A. Ariger、Henar Vázquez-Villa、Erick M. Carreira
DOI:10.1021/ol1008894
日期:2010.7.2
Catalytic reduction of α-substituted acetophenones under conditions involving asymmetric transfer hydrogenation in water is described. The reaction is conducted in water and open to air, and formic acid is used as reductant.
A direct catalyticasymmetricaddition of acetonitrile to aldehydes that realizes over 90 % ee is the ultimate challenge in alkylnitrile addition chemistry. Herein, we report achieving high enantioselectivity by the strategic use of a sterically demanding NiII pincer carbene complex, which afforded highly enantioenriched β‐hydroxynitriles. This highly atom‐economical process paves the way for exploiting
Unexpected Stereorecognition in Nitrilase-Catalyzed Hydrolysis of β-Hydroxy Nitriles
作者:Sukanta Kamila、Dunming Zhu、Edward R. Biehl、Ling Hua
DOI:10.1021/ol061542+
日期:2006.9.1
Biocatalytic enantioselective hydrolysis of beta-hydroxy nitriles to corresponding (S)-enriched beta-hydroxy carboxylic acids has been achieved for the first time by an isolated nitrilase bll6402 from Bradyrhizobium japonicum USDA110. This offers a new "green" approach to optically pure beta-hydroxy nitriles and beta-hydroxy carboxylic acids. The observed remote stereorecognition is surprising because
alpha-Ethylation is competing with the biocatalytic reduction of aromatic beta-ketonitriles in a whole-cell system. Use of two newly mined robust and stereo-complementary carbonyl reductases in a biphasic system has completely eliminated the competing byproduct For the first time, both enantiomers of fluoroxetine precursors were obtained at 0.5 M with >99% ee and excellent chemoselectivity, without addition of any external cofactors.