Glycosidation of 3,4,6-tri-O-benzyl-2-ethenyl-D-glucal - A route to 2-C-(beta-methyl)methylene glycosides

Monosaccharidic and disaccharidic 2-C-(beta-methyl)methylene glycosides wer e synthesized by an electrophilic conjugate addition reaction of ROH-type c ompounds in the presence of Ph3+PH Br- to 2-ethenyl-3,4,6-tri-O-benzyl-D-gl ucal 1, functioning as a model glycosyl donor. This 2-vinyl glucal derivati ve represents a series of 2-vinyl, and 2-butadienyl glycals, prepared by Wi ttig-type methylenation of pyranosidic conjugated enals, derived from gluca l, galactal and lactal. The exo-(beta-methyl)methylene group paves the way for further chemical transformations.