Glycosylating reagents

Two- and three-component Hantzsch reactions using C-glycosylated reagents have been reported as an alternate method for conducting asymmetric syntheses of 1,4-dihydropyridines." ° Reaction of 109, 110 and 97 generate 111 with Ri = sugar. Alternatively, 112 and 113 produce 111 with Ri = sugar. While the yields were acceptable (60-90%), the diastereomeric ratio varied from 30-60%. 

Table II. They showed that tryptophan, IAA and IAA-myo-inositol are turning over—that is made and then destroyed, or used, at rates such that tJj was 5, 3.2 and 12 hrs, respectively. Such data permitted several important conclusions concerning the metabolism of these compounds, for example, that it is the IAA esters, and not tryptophan, which serve as a source of IAA for the germinating seed and secondly that the IAA-inositols are turning over at such a rapid rate that they must be in equilibrium with the IAA-myo-inositol glycoside pool perhaps acting as glycosylation reagents (Epstein, unpublished).

S. Aoki, H. Kondo, and C.-H. Wong, Glycosyl phosphites as glycosylation reagents, Methods Enzymol., 247 (1994) 193-211. 

Kondo H, Aoki S, Ichikawa Y, Halcomb RL, Ritzen H, Wong C-H (1994) Glycosyl phosphites as glycosylation reagents scope and mechanism. J Org Chem 59 864-877... 

The use of anomeric sulfoxides as glycosylating reagents was reported by Kahne and coworkers in 1989 [51]. Upon activation with triflic anhydride at low temperatures, anomeric sulfoxides are transformed into extremely reactive glycosyl donors, which can glycosylate very hindered acceptors. The excellent reactivity of the sulfoxide donors coupled with the selectivity achieved by use of a participating group in the C2 position prompted their use in the synthesis of oligosaccharides on the solid support [52]. 

P. J. Garegg, B. Samuelsson, P. Konradsson, I. Kvamstrom, and S. C. T. Svensson, Novel glycosylation reagents synthesis of disaccharides containing 2-deoxy-2-iodo-a-D-talopyranosyl groups, Carbohydr. Res., 92 (1981) 157-159. 

Glycosyl bromides continue to hold primary place as glycosylation reagents Tl , Co and Cd salts of zeolites 4A and 3X are suitable... 

Compound (28) is a key glycosylating reagent for making disaccharides having 2-amlno-2-deoxy-D-glucose at the non-reducing end ... 

---