D-Galactopyranose

Fig. 9. Partial structural formulas and shorthand notations for principal hemiceUuloses found in wood, where the sugar units ate noted as P-D-xylopyranose (Xylp), 4-Omethyl-a-D-glucopyranosyluronic acid (GlupU), a-L-arabinofuranose (Araf), P-D-glucopyranose (Glup), P-D-mannopyranose (Manp), and P-D-galactopyranose (Galp) for (a) arabino-4-O-methylglucuronoxylan from softwood, (b) 0-acetyl-galactoglucomannan from softwood, and...

Galactose differs from glucose in configuration at C-4. The C-4 hydroxyl is axial in p-D-galactopyranose, but it is equatorial in p-o-glucopyranose. ... 

From the rearrangement of tetra-O-acetyl-2-hydroxy-D-galactal in boiling acetic acid it was possible to isolate l,2,4,6-tetra-0-acetyl-2,3-dide-h.ydro-3-deoxy-a-jy-threo-hexose (32) (58%) and a small amount of 1,2,3,4,6-penta-O-acetyl-jS-D-galactopyranose. In the reaction mixture the presence of some a-pentaacetate was demonstrated chromatographically but NMR spectroscopy indicated no resonances corresponding to the / anomer of compound 32. These spectral measurements indicate that compound 32 constituted 80% of the mixture of products. 

The only recorded example using this method in the sugar series is the chlorination of l,2 3,4-di-0-isopropylidene-D-galactopyranose (73) which affords in addition to the expected 6-chloro-6-deoxy derivative 74a, a 5,6-unsaturated derivative 75 as well. These products were separated by silica gel column chromatography no yields were given. 

Deoxy-p-D-xy/o-hexopyranose 2-Deoxy-D-ribo-hexose not 2-deoxy-D-allose not 4-deoxy-p-D-galactopyranose... 

Starting from (—)-29, carba-a-D-galactopyranose (7) and carba-) -D-glu-copyranose (94) have been synthesized by a reaction analogous to that employed in the preparation of the racemates. - ... 

Carba-a-D-galactopyranose (7) has also been synthesized from quebrachi-tol, by Paulsen and coworkers,as well as carba- -D-mannopyranose (114). 

Difluoro compounds have been prepared by treatment of carbonyl compounds with DAST. These are methyl 5-deoxy-5,5-difluoro-2,3,-0-isopropylidene-)S-D-ribofuranoside, 6-deoxy-6,6-difluoro-1,2 3,4-di-0-isopropylidene-a-D-galactopyranose, methyl 2-deoxy-2,2-difluoro-... 

Deoxy-3-[ F]fluoro-D-glucose ( F-3DFG) was prepared - 454,467,473-476 essentially according to the procedure for the cold synthesis (see Section 11,2), namely, treatment of248 with Cs F (in DMF or HMPA), tetraalkylammonium [ F]fluoride (DMF, HMPA, or MeCN) or K F (in acetamide). 6-Deoxy-6-[ F]fluoro-a-D-galactopyranose was likewise pre-pared aceording to the cold synthesis. ... 

Agarose is closely approximated as the alternating copolymer of (1 3)-/3-D-galactopyranose and (l- 4)-3,6-anhydro-a-L-galactopyranose (see formula 5). 

Acetamido-2-deoxy-D-galactopyranose (—), and 2-Acetamido-2-deoxy-D-mannopyranose ( ) at Anomeric Equilibrium in Aqueous Solution (redrawn from Ref. 28), and 2-Acetamido-2-deoxy-D-glucopyranose (- -) at Anomeric Equilibrium in Aqueous Solution. (Redrawn from Ref. 29.)... 

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