Mannose preparation

Gelas and D. Horton, Kinetic acetonation of D-mannose preparation of 4,6-mono and 2,3 4,6-di-0-isopropylidene-D-mannose, Carbohydr. Res. 67 371 (1978). 

D (+) Galactose is a constituent of numerous polysaccharides It is best obtained by acid hydrolysis of lactose (milk sugar) a disaccharide of d glucose and d galactose L (—) Galactose also occurs naturally and can be prepared by hydrolysis of flaxseed gum and agar The principal source of d (+) mannose is hydrolysis of the polysaccharide of the ivory nut a large nut like seed obtained from a South American palm... 

Pentenomycin (33), a highly oxygenated cyclopentenoid with a quaternary chiral center (Scheme 6), was prepared by a similar reaction sequence [29]. The RCM precursor 31 was prepared in eight steps from D-mannose via iodo compound 29 and aldehyde 30 (1 1 diastereomeric mixture). RCM of 31 led to the epimeric cyclopentenols 32. 

Chiral nitrogen chelates derived from sugars were prepared by Ruffo [48], introducing diimines and diamines functionalities on inexpensive monoses, a-D-glucose and a-D-mannose. 

Deoxy-3-fluoro-D-glucose (25%) and -mannose (40%) were prepared from 2-deoxy-2-fluoro-D-arabinose by a chain-extension reaction (cyanohydrin synthesis). Likewise, 4-deoxy-4-fluoro-D-glucose ° (27%) and -mannose (45%) were prepared from 3-deoxy-3-fluoro-D-arabinose. ... 

Deoxy-2-[ F]fluoro-D-mannose ( F-2DFM) was prepared through treatment of 201 (see Section 11,2) with F-Bu4NF(MeCN, 75°, 30 min) or K F crown ether, as reported for the cold synthesis. F-2DFM was also prepared from methyl 4,6-di-0-acetyl-3-C>-benzoyl-2-C>-triflyl-a-D-glu-copyranoside with amino(polyether)-supported, carrier-free [ F]fluoride. 

As 2-amino-2-deoxy-D-mannose is tumorstatic and 2-acetamido-2-deoxy-D-mannose 6-phosphate is an obligatory intermediate in the biosynthetic pathway to sialic acid, displacement of the essential OH-6 with a fluorine atom should be interesting from the biological viewpoint. 2-Acetamido-1,3,4-tri-0-acetyl-2,6-dideoxy-6-fluoro-D-mannopyranose (see Table 111 in Section 11,3) and its O- and A,0-deacetyl derivatives were prepared the first compound showed weak anticancer activity. 

Probably the most promising polymeric drug carrier system involves polysaccharide molecules. These are natural polymers and are often biodegradable to products that are useful to the host or easily eliminated by the host. Dextrans have been the most extensively used polysaccharide for macromolecular prodrug preparations (79). These materials are biocompatible and the in vivo fate is directly related to their molecular weight. Moreover these macromolecules can be easily targetted to the hepatocytes with D-mannose or L-fucose (20). 

The formation of D-glucose phenylosazone from chitosamine showed its relationship to D-glucose and D-mannose and Irvine and Hynd7 succeeded in preparing both D-mannose and D-glucose from chitosamine. 

---