Primary allylic amines with enantiomeric excesses from 97 to >99% were prepared by asymmetric transfer hydrogenation of α,β-unsaturated N-(tert-butylsulfinyl)ketimines followed by removal of the sulfinyl group. The effect caused by different substituents at the C═C bond and at the iminic carbon atom on the chemoselectivity of the reduction was studied. The desired enantiomer of the final allylic amine
Asymmetric synthesis of α-chiral ketones by the reduction of enones with baker's yeast
作者:Yasushi Kawai、Motoko Hayashi、Norihiro Tokitoh
DOI:10.1016/s0957-4166(01)00537-7
日期:2001.11
asymmetric reduction of α,β-unsaturatedketones (enones) having a pyridyl ring affords the corresponding optically active α-substituted ketones (α-chiral ketones) with excellent stereoselectivity. The position of the heteroatom, as well as the bulk of the α-substituent, plays an important role in governing the stereoselectivity in the reduction of a carboncarbon doublebond.
The ene-reductases mediated bioreduction of a selection of open-chain α-alkyl-β-aryl enones afforded the corresponding saturated α-chiral ketones in high yield and optical purity in several cases. The stereo-electronic requirements of the reaction have been investigated, considering the nature and location of substituents on the aromatic ring as well as the steric hindrance at the α-position and adjacent
Straightforward Synthesis of All Stenusine and Norstenusine Stereoisomers
作者:Tobias Müller、Konrad Dettner、Karlheinz Seifert
DOI:10.1002/ejoc.201100612
日期:2011.10
All the stereoisomers of stenusine (1) and norstenusine (21) have been efficiently synthesized by the asymmetrichydrogenation of pyridines. The (2R,3S)- and (2R,3R)-isomers of 1, that are difficult to prepare, have been synthesized for the first time using a chemoenzymatic approach in eight steps with an 8 % total yield. All the target compounds were obtained in good stereochemical purity by using