ALPHA-HYDROGEN AND BETA-HYDROGEN ELIMINATIONS IN THE REACTIONS OF SOME 3-O-TRIFLYLGLYCOSIDES WITH (BUOK)-BU-T AND PYRIDINE

Previous papers [10-12] reported new reactions that occur when some ca rbohydrate triflates are treated with MeLi (or BuLi) in Et2O to give t he C-methyl(butyl) or unsaturated compounds through elimination of the CH-hydrogen bearing a CF3SO3 group ( alpha-elimination) as a proton. This paper extends the previous work and describes the reactions for s ome 3-O-triflyl-D-gluco- and -allo-furanosides and -pyranosides with ( BuOK)-Bu-t and pyridine [instead of Me(Bu)Li], utilizing the correspon ding 2- and 3-deuterated analogs. II was found that, when (BuOK)-Bu-t was used, the 3-O-triflyl-D-glucopyranosides gave 2,3- and 3,4-unsatur ated compounds through alpha-hydrogen elimination (alpha-elimination) followed by (possibly) C-3 carbene formation, while the 3-O-triflyl-D- allopyranosides gave mainly 2,3-unsaturated compounds through alpha-el imination. When pyridine was used, most of the compounds gave the corr esponding 3-pyridinium derivatives through an SN2 process. (C) 1997 El sevier Science Ltd.