Lewis acid promoted anomerisation of alkyl O- and S-xylo-, arabino- and fucopyranosides.

Pentopyranoside and 6-deoxyhexopyranosides, such as those from d-xylose, l-arabinose and l-fucose are components of natural products, oligosaccharides or polysaccharides. Lewis acid promoted anomerisation of some of their alkyl O- and S-glycopyranosides is reported here. SnCl was more successful than TiCl, with the latter giving the glycosyl chloride by-product in some cases, and both were superior to BFOEt.

Catalyst-Free Formal Thioboration to Synthesize Borylated Benzothiophenes and Dihydrothiophenes.

The first ring-forming thioboration reaction of C-C π bonds is reported. This catalyst-free method proceeds in the presence of a commercially available external electrophilic boron source (B-chlorocatecholborane) in good to high yields. The method is scalable and tolerates a variety of functional groups that are intolerant of other major borylation methods.