Site-Selective Dehydroxy-Chlorination of Secondary Alcohols in Unprotected Glycosides

To circumvent protecting groups, the site-selective modification of unprotected glycosides is intensively studied. We show that site-selective oxidation, followed by treatment of the corresponding trityl hydrazone with tert-butyl hypochlorite and a H atom donor provides an effective way to introduce a chloride substituent in a variety of mono-and disaccharides. The stereoselectivity can be steered, and a new geminal dichlorination reaction is described as well. This strategy challenges existing methods that lead to overchlorination.

Automated summary

This study presents a method for site-selective modification of unprotected glycosides without the need for protecting groups. By employing site-selective oxidation and specific treatment steps, the introduction of chloride substituents and control over stereoselectivity is achieved.