1,6-ANHYDRO-BETA-D-GLUCOPYRANOSE IN ORGANIC-SYNTHESIS - PREPARATION OF A FRAGMENT FOR THE SYNTHESIS OF ROSARAMYCIN

1,6-Anhydro-β-d-glucopyranose has been used as the starting material for a synthesis of ethyl (E)-4-C-allyl-2,3,4,6-tetradeoxy-5,7-O-isopropylidene-8-O-methanesulphonyl-2,6-di-C-methyl-d-gulo-oct-2-enoate, which represents a synthetic unit equivalent to C-2/9 of the macrolide antibiotic rosaramycin. The synthesis involved a minimum of chromatography, and the extremely high level of regiochemical and stereochemical control was achieved by the use of epoxides at crucial CC-bond-forming steps. A method was also developed, using tosylmethyl isocyanide, which converted a carbohydrate 6-aldehyde (19) directly into the corresponding homologated methyl ester. © 1990.