Glycosylamines synthesis

Stereoselective Strecker reactions with galactosylamine 1 can also be achieved with sodium cyanide and acetic acid in 2-propanol. The reactions, however, proceed slowly and with a lower stereoselectivity, giving diastereomeric ratios of the products between 3 1 and 7 1. The scope of the method can be extended to other glycosylamines, e.g., 2,3,4-tri-O-pivaloyl-a-D-arabinosyl-amine which allows the stereoselective synthesis of (A )-amino nitriles61,62. 

Ferndndez-Bolanos JG, Lopez 6 (2007) Synthesis of Heterocycles from Glycosylamines and Glycosyl Azides. 7 31-66... 

The following protocol for synthesis of glycosylamines from reducing sugars is based on the method of Likhosherstov et al. (1986). 

Bajugam and Flitsch [217] have described the synthesis of glycosylamines from mono-, di-, and trisaccharides by direct microwave-assisted Kochetkov amination (Scheme 6.110). The reaction was found to be effective with just a fivefold excess (w/w) of ammonium carbonate with respect to the sugar, as compared to the 40-or 50-fold excess needed under thermal conditions. All transformations were completed within 90 min in dimethyl sulfoxide as solvent, maintaining the vessel temperature at an apparent 40 °C using the heating-while-cooling technique (see Section 2.5.3). 

Synthesis of ds-fused OZT starting from 2-amino-2-deoxy-D-glucose and D-mannose hydrochlorides in conditions similar to those applied for glycosylamines was recently published (Scheme 6).36 In contrast with data previously reported for tram-fused thiocarbamate,32 the isomeric isothiocyanates were not detected. 

A number of publications on glycopeptide chemistry have appeared since this manuscript was submitted. Cohen-Anisfeld and Lansbury (94) reported on a convergent synthesis of glycopeptides. Peptides containing aspartic acid unblocked at the / -carboxy group were synthesized and, subsequently, condensed with glycosylamines. 

Two bases approaches are used in the synthesis of sugar carbamides direct interaction of carbohydrates with carbamides and their analogs in the conditions of acid catalysis (a) and interaction of acetylation N-glycosylisothiocyanates with amines (b) or interaction of acetylation N-glycosylamines with arylisothiocyanates (c) [3],... 

Most frequently, sugar O-acetates have been used in N-linked glycopeptide synthesis. The protection of the glycosylamines as O-acetates requires two steps in the deprotection procedure after glycopeptide assembly. 

---