Synthesis of 4-O-α-D-Mannopyranosyl-L-rhamnopyranose

Abstract

4-O-α-D-Mannopyranosyl- L-rhamnopyranose has been synthesized in 55% yield by condensation of 2,3,4,6-tetra-O-benzoyl- α-D-mannopyranosyl bromide with methyl 2,3-O-isopropylidene-α-L-rhamno-pyranoside using mercuric cyanide in acetonitrile (Helferich reaction). The disaccharide has m.p. 143–145°, [α]D + 53.0° → 60.3° (c, 1.0 water), and was characterized as the crystalline peracetates of the disaccharide (m.p. 149.5–150.5°, [α]D − 4.4° (c, 4.3 chloroform)) and of the derived alditol (m.p. 84−85°, [α]D −4.4° (c, 1.9 chloroform)).