SYNTHESIS OF METHYL D-MANNOFURANOSIDES AND OF 5-O-METHYL-D-MANNOSE

Kuhn methylation of 2,3:5,6-di-O-isopropylidene-d-mannofuranose affords a mixture of methyl 2,3:5,6-di-O-isopropylidene-α-d-mannofuranoside and methyl 2,3:5,6-di-O-isopropylidene-β-d-mannofuranoside, in the ratio 99:1. Treatment of the sodio derivative of the di-acetal with methyl iodide gave the same products, but the ratio was reversed and was 10:1 in favour of the β-d-anomer. Convenient procedures for the synthesis of methyl α-d-mannofuranoside and methyl β-d-mannofuranoside from the corresponding di-acetals are described, and a synthesis of 5-O-methyl-d-mannose is also presented. © 1969.