摘要:
Abstract3‐O‐benzyl (and 3‐O‐methyl)‐1,2‐O‐isopropylidene‐α‐D‐xylo‐dialdo‐1,4‐furanoses treated with bromocyanomethylidene‐ or bromoacylmethylidene‐triphenylphosphoranes gave in good yields the corresponding olefinic sugars. These compounds, which bear three adjacent electrophilic carbon atoms (C(5), C(6), C(7)) constitute useful synthetic intermediates in carbohydrate chemistry. They represent, for example, good starting materials for the preparation of 3‐glycosylisoxazoles, 5‐glycosylisoxazoles and 2‐glycosylthiophenes.