REACTIONS OF CARBOHYDRATES WITH (HALOMETHYLENE)DIMETHYLIMINIUM HALIDES AND RELATED REAGENTS . SYNTHESIS OF SOME CHLORODEOXY SUGARS

The reaction of (chloromethylene)- and (chloroethylidene)dimethyliminium chloride with selected carbohydrate derivatives containing hydroxyl, epoxide, and unsaturated functions has been investigated. Primary hydroxyl groups are converted into formate esters or are replaced by a chlorine atom, depending on the reaction conditions. Acetal and ketal groups migrate in certain cases, especially when the hydroxyl group is secondary. The reagent reacts with methyl 2,3-anhydro-4,6-O-benzyIidene-α-D-allopyranoside to give the trans-2-chloro deoxy-3-formate derivative, as a result of nucleophilic attack of chloride ion on the epoxide function. At elevated temperature a second chlorine atom is incorporated into the molecule with acetal migration to give methyl 3,4-0-benzylidene-2,6-dichloro-2,6-dideoxy-α-D-altropyranoside. The mechanism of the reaction is discussed. © 1969, American Chemical Society. All rights reserved.