Facile, Highly Selective Synthesis of α‐ and β‐Disaccharides from 1‐ O ‐Metalated D ‐Ribofuranoses

α- and β-Disaccharide syntheses not requiring halogenoses and heavy metals have many advantages. Depending on the nature and size of the 5-O-substituent R, compound (1) is metalated to give (2) (R  H) or (3) (R  CPh3, tBuMe2Si); (2) is a precursor of β-, and (3) a precursor of α-disaccharides