Reactions of some 2- and 4-O-triflylglycopyranosides with MeLi, t-BuOK, and pyridine

摘要

As an extension of our previous work on secondary triflates of carbohydrates [El Nernr, A.; Isuchiva. T. Tetrahedron Lett. 1995. 36. 7665— 7668. El Nemr, A.; Tsuchiya, T.; Kobayashi, Y. Garbol2vdr. Res. 1996, 293. 31— 59. El Nemr, A.; Tsuchiya, T. Carbohvdr. Res. 1997, 301, 77—87. El Netnr, A.; Tsuchiya, T. Carbohvdr. Res. 1997. 303. ‘67—281] the reaction modes of several methyl 2- and 4-0-triflyl-o-glycopyranosides with MeLi (strong basci. t-BuOK (moderately strong base), and pyridine (weak base) have been studied. This paper describes the reactions cm 3-0-benzyl-4,6-0-benzylidene-2-0-triflyl-o-gluco and -mannopyranosides with MeLi to give mainly the correspond-ing 2-C-rn ethyl derivatives through u-elimination. with t-BuOK to give either the 2,3-unsaturated compounds through a-elimination or detriflyl ~-ols and with hot pvridine to give the corresponding 2-pyridinium salts with inversion (except for the 2-0 -triflyl-~-n-mannopyranoside (8)). 2.3 .6-Tn- 0 -benzyl-4- 0 -triftyl-~-D-gluco and-mannopyranosides were also examined similarly.