Glycosylation phosphorus

Phosphorylation of protected D-glucopyranose and D-galactopyranose with dioxaphosphorinane or 6-methyldioxaphosphorinane gave the corresponding glycosyl phosphorus derivatives (1). Similarly prepared were the phosphono-diamidite and benzyl phosphonoamidite derivatives (2) and (3). Treatment of... 

In a similar vein, reaction of the readily accessible xanthine (39-1) with the ubiquitous phosphorus oxychloride affords the enol chloride (39-2). Alkylation of the anion obtained from that product with a base with the chloro deoxy sugar (39-3) leads to the glycosylated product (39-4). Treatment with ammonia selectively replaces the halogen at the 6 position. The protecting groups on the sugar are cleaved in the course of the reaction to afford cladribine (39-4) [41]. 

For purposes of classifying the reactions of metabolism, in this book the nucleophilic displacements are grouped into four subtypes (Table 10-1). These are displacements on (A) a saturated carbon atom, often from a methyl group or a glycosyl group (B) a carbonyl group of an ester, thioester, or amide (C) a phospho group or (D) a sulfur atom. In addition, many enzymes employ in sequence a displacement on a carbon atom followed by a second displacement on a phosphorus atom (or vice versa). 

Di-0-isopropylidene-D-mannosyl chloride has been prepared from di-O-isopropylidene-D-mannose by the action of phosphorus penta-chloride in light petroleum in the presence of anhydrous sodium carbonate. Hepta-O-methylcellobiose and tetra-O-methyl-D-glucopyranose have been converted to the corresponding glycosyl chlorides by the same method. ... 

Glycosyl Phosphites, Phosphates and Other Phosphorus Compounds... 

Glycosyl thio compounds with phosphorus in the leaving group have also been studied. 

A variety of glycosyl derivatives with both trivalent and pentavalent phosphorus atoms in the leaving group is known and was investigated as glycosyl donors. 

Besides glycosyl phosphites and phosphates, a variety of other phosphorus containing leaving groups have been designed and proposed. These are summarized in Table 4.11. 

Among glycosyl donors possessing pentavalent phosphorus, glycosyl dimethylphosphino-thioates 217 were introduced by Inazu and coworkers, and were used with AgC104 [485-487], l2-TrC104 [486-489] or TrC104 [490] activators. 

Additional types of phosphorus donors include the glycosyl diphenylphosphinates 221, which were used in TMSOTf-promoted reactions [471,474], whereas reaction of difluorophosphates 222 was assisted by AgC104 [497]. 

Phosphorus-containing leaving groups with glycosyl-sulfur linkages such as dithiophosphates and phosphorodiamidimidothioates were discussed in Section 4.3.2.3. 

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