An efficient approach to partially O-methylated α-D-mannopyranosides using bis-tert-butyldiphenylsilyl ethers as intermediates

Article abstract of DOI:10.1016/0040-4020(96)00600-X

Differential migratory aptitudes of secondary tert-butyldiphenylsilyl (DBDPS) groups have been observed for the bis-silylated derivatives of methyl and allyl α-D-mannopyranosides under several basic media. A remarkable variation of the selectivity in the migration of the TBDPS group at position 3 (O-3 → O-2 versus O-3 → O-4) was found by changing the hardness of the base and reaction conditions. This behaviour was directed towards the practical synthesis of the 3,6-, 2,6- and 4,6-bis-TBDPS ethers, 3-5a,b, versatile intermediates for the preparation of other O-substituted derivatives. Their conversion into the methyl and allyl 2,4-, 3,4- and 2,3-di-O-methyl α-D-mannopyranosides (10-12a,b) was successfully achieved.