Convenient approach to chiral 4-monosubstituted 1,3-oxazolidine-2-thiones

ABSTRACT

Chiral 4-monosubstituted 1,3-oxazolidine-2-thiones are regarded as one of the modified version of Evans auxiliaries in asymmetric aldol condensation, which can generate two adjacent chiral carbon centers in one time They have advantages over Evans auxiliaries in some aspects, however, their application is highly limited by their preparation approaches as toxic or flammable chemicals are involved. Here, a mild and applicable procedure for preparing the chiral oxazolidine-2-thione auxiliaries has been developed in this article. Potassium ethylxanthate and the corresponding chiral amino alcohols as the starting material in absolute ethanol are mixed and the mixture are heated under reflux for 1 h in open air to provide 1,3-oxazolidine-2-thiones chiral auxiliaries in moderate to excellent yields.

GRAPHICAL ABSTRACT

KEYWORDS:

• 1,3-Oxazolidine-2-thione
• chiral auxiliaries
• environmentally-benign
• xanthates

Additional information

Funding

This project is supported by the National Natural Science Foundation of China (Nos. 21572118 and 21572080) and Jiangsu University (Nos. 10JDG042 and 14JDG018).