Rh-Catalyzed Asymmetric Hydrogenation of β-Substituted-β-thio-α,β-unsaturated Esters: Expeditious Access to Chiral Organic Sulfides
作者:Gang Liu、Zhengyu Han、Xiu-Qin Dong、Xumu Zhang
DOI:10.1021/acs.orglett.8b02339
日期:2018.9.21
Rh/bifunctional bisphosphine-thiourea ligand (ZhaoPhos)-catalyzed asymmetric hydorgenation of both (Z)- and (E)-isomers of β-substituted-β-thio-α,β-unsaturated esters was successfully developed. This new asymmetric catalytic methodology provided highly efficient access to two enantiomers of chiral organic sulfides ethyl β-substituted-β-thio-propanoates with excellent results (up to 99% yield and >99%
The reaction of benzenethiol with ethylbenzoylacetate in polyphosphoric acid (PPA) at low temperature gave mainly ethyl 3-phenyl-3,3-bis(phenylthio)propionate 8 as an intermediate in the synthesis of thioflavones, while that from t-butylthiobenzene under similar conditions gave ethyl 3-(phenylthio)cinnamate 7 as a major product and many by-products. The reaction constant for intramolecular cyclic