An improved method for the preparation of some ethyl 1-thioglycosides

Ethyl 1-thioglycosides were prepared in almost quantitative yield from sugar peracetates in 3:2 chloroform-ether, with boron trifluoride diethyl etherate as catalyst. d-Galactose, d-glucose, and 2-deoxy-2-phthalimido-d-glucose yielded almost exclusively β anomers, whereas l-rhamnose and d-mannose resulted predominantly in the α anomers.