D-Galactose derivatives

R = 1-BuMe2Si, = a, then D-glucose derivative,b)— = p,then D-galactose derivative... 

Fig. 4. 2-Amino-2-deoxyglycoseptanosides prepared using D-glucose- and D-galactose-derived septan-sosyl donors 72 and 74, (Shown in Scheme 14) respectively.

Alkyl (or acyl) derivatives of the 6-amino-6-deoxy carbohydrates are examples of derivatives in which the hydrophilic and hydrophobic moieties are linked at other positions than C-1. Thus 6-amino-6-deoxy-D-galactose derivatives 34 were prepared from l,2 3,4-di-0-isopropylidene-6-0-tosyl-a-D-galacto-pyranose by the following reactions (1) substitution of the leaving group at C-6 by a phthaloyl function, (2) hydrazinolysis to afford a 6-amino-6-deoxy intermediate, (3) reaction of acyl or sulfonyl chlorides at the amino function, (4) deprotection of the acetal rings to afford the expected glycolipid 34 [56]. 

Nitrile imines are related to azomethine imines, in the same manner as nitrile oxides are related to nitrones. In a single and recent report, the reactions of D-galactose derived chiral nitrile imines have been described (104). However, in reactions with nonchiral alkenes, no diastereoselection was obtained. 

Thymidine 5 -(a-D-glucopyranosyl pyrophosphate) (4) and the analogous D-galactose derivative have been isolated from extracts of Pasteurella pseudo tuberculosis.102 The ester of thymidine 5 -pyro-phosphate with a-D-mannopyranose was found in an extract of Strep-tomyces griseus,14,103 and the occurrence of the D-ribosyl ester in the... 

The methylated D-galactose derivatives 66 and 67 were thereafter released by mild hydrolysis with acid. The product was reduced with sodium borodeuteride, the reduction product methylated with trideuteriomethyl iodide, and the ether analyzed. From the disappearance of the ethers derived from the uronic acid and the 2-substi-tuted L-rhamnose, and the appearance of the ethers 68 and 69, the... 

In addition, by using various D-galactose derivatives, deductions could be made with regard to the contributions of portions of the Gal2 molecule to its total binding-energy with these two im-... 

Nishida, Y. Ohrui, H. Meguro, H. H-NMR studies of (6R)- and (6S)-deuterated D-hexoses Assignment of the preferred rotamers about C5—C6 bond of D-glucose and D-galactose derivatives in solutions, Tetrahedron Lett. 1984, 25, 1575-1578. 

For example, the three-component domino inter-[4- -2]/inter-[3- -2] cycloaddition reaction of the D-galactose-derived heterodiene 538 with ethyl vinyl ether and methyl vinyl ketone took place with total chemo-, regio-, facial-, and stereoselectivity to give a single nitrosoacetal 539 in 70% yield (Equation 89) <1998CC459>. 

The aforementioned D-galactose-derived chiral imines 27 were used for the Strecker synthesis of D-a-amino nitriles and D-o -amino acids by the Kunz group. Various types of glycosylim-ines 27, prepared from 2,3,4,6-tetra-0-pivaloyl-/3-D-galacosylamine with aliphatic or aromatic aldehydes, were treated with TMSCN in the presence of SnCl4, providing a-amino nitriles... 

The procedure is remarkably effective for the coupling with cyclic ketones and provides a fast access to a-C-ketosides of Neu5Ac. The coupling efficiency is however moderate in the synthesis of C-disaccharides, as shown with the D-galactose-derived aldehyde 198 (O Scheme 44). Acetates 213 provide the expected compound 215 but much less efficiently than sulfide 204 (30 versus 82% yield, respectively). The moderate yield using acetates 213 is due to the competitive pinacol coupling of aldehyde 198 because the rate of the reductive metallation of the anomeric acetates is too slow. 

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