Galactopyranosyl-a-D-mannopyranoside

Kishi and co-workers have proposed that O-glycosides and C-glycosyl compounds share the same conformational characteristics in solution.34 This is the case, for instance, for the C-disaccharide 27 (Fig. 15).35 It adopts a major conformation similar to that proposed for methyl 3-<9-(a-n-galactopyranosyl)-a-D-mannopyranoside (28). 

Oxidation of lactal with perbenzoic acid and anhydrous methanol leads to methyl 4-(/3-D-galactopyranosyl)-a -D-mannopyranoside (LVII)48-6 ... 

A rational design and synthesis of (3-0-carboxymethyl)-/3-D-galactopyranosyl-a-D-mannopyranoside (22) provided a disaccha-... 

Fig. 3. Proton-detected carbon-13 spin-lattice relaxation for the pentasaccharide p-trifluorao-acetamidophenyl-2,6-di-0-[/3-D-galactopyranosyl-(l 4)-0-2-acetamido-2-deoxy-/3-D-glu-copyranosyl]a-D-mannopyranoside. The measurements were performed with the two-dimensional method proposed by Skelton et al. [21], modified to obtain a one-dimensional pulse sequence. The figure shows the measurements for Cl in the 2-acetamido-2-deoxy-glucopyranose residue attached at position 2 on the mannopyranose residue.

Similar reactions have been observed with 8-D-galactopyranosyl fluoride and a-D-mannopyranosyl fluoride. In this latter example, the epoxide ring in the supposed intermediate [(8)] would not be favorably located for internal-glycoside formation with the C-6-hydroxyl group the only observed product is methyl a-D-mannopyranoside (9). 

Benzyl 2,3-anhydro-4-0-a-L-arabinopyranosyl-p-D-ribopyranoside, A-848 Benzyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside, A-484 Benzyl 2,3-anhydro-4,6-0-benzylidene-p-D-gulopyranoside, A-639 Benzyl 2,3-anhydro-4,6-0-benzylidene-a-D-mannopyranoside, A-676 Benzyl 3,4-anhydro-2,6-dideoxy-a-L-r -hexopyranoside, A-591 Benzyl 2,3-anhydro-4- O - p-D-galactopyranosyl- p-D-ribopyranoside, G-173 Benzyl 2,3-anhydro-a-D-mannopyranoside, A-676 Benzyl 2,3-anhydro-p-D-mannopyranoside, A-676 Benzyl 3,4-anhydro-2-0-mesyl-6-0-trityl-a-D-altropyranoside, A-495 Benzyl 2,3-anhydro-4-0-methyl-p-D-ribopyranoside, A-693 Benzyl 2,3-anhydro-p-D-ery /iro-pentopyranosid-4-ulose, A-682 Benzyl 2,3-anhydro-p-L-eyy /iro-pentopyranosid-4-ulose, A-682 Benzyl 2,3-anhydro-a-D-ribopyranoside, A-693 Benzyl 2,3-anhydro-p-D-ribopyranoside, A-693 Benzyl 2,3-anhydro-p-L-ribopyranoside, A-693... 

Methyl 3,4,6-tri-O-acetyl-2-O-(2,3,4,6-tetra-O-acetyl-p-i>-galactopyranosyl)-a-i>allopyranoside, G-39 Methyl 3,4,6-tri-0-acetyl-2-S-(2,3,4,6-tetra-0-acetyl-a-D-glua>pyranosyl)-2-thio-p-D-glucopyranose, T-78 Methyl 2,4,6-tri-0-acetyl-3-0-(2,3,4,6-tetra-0-acetyl-a-D-mannopyranosyl)-a-D-mannopyranoside, M-93 Methyl 2,3,6-tri-0-benzoyl-4-0-(2,3,4,6-tetra-0-benzoyl-p-i>-galactopyranosyl)- p-i>-allopyranoside, G-40 Methyl 2,4,6-tri-0-l5enzyl-3-0-(3,4,6-tri-0-benzyl-P-D-mannopyraiiosy -a-D-mannopyranoside, M-97 Methyl p-turanopyranoside, T-201... 

Acetamido-4-amino-2,4,6-trideoxy-D-galactopyranosyl precursors such as trichltHoacetimidate 76, were prepared from ethyl 1-thio-a-D-mannopyranoside. Key steps were stereoselective reduction of oxine 74 (available in 5 steps), and azidonitration of glycal 75 (Scheme 23). Their application in the synthesis of disaccharides is covered in Chapter 3. Benzyl 2,4-diacetamido-3-6>-benzyl-2,4,6-trideoxy-P-D-galactopyranoside has been synthesized in 5 steps from benzyl 2-acetamido-3-6>-benzyl-2-deoxy-P-D-galactopyranoside. ... 

The disaccharides a-D-galactopyranosyl a-D-galactopyranoside, a-D-allopyr-anosyl a-D-allopyranoside, 3,3, 4,4 -tetra-0-benzoyl-2,2, 6,6 -tetradeoxy-a,a-ribotrehalose 3, 2,3,4,6,r,3, 4, 6 -octa-0-acetyl-P-sophorose, methyl 2,3,4,6,3, 4, 6 -hepta-0-acetyl-P-sophoroside, methyl 2,3,4,6,3, 4 -hexa-0-acetyl-6 -deoxy-P-sophoroside and methyl 2-0-(2,3,4-tri-0-acetyl-P-D-xylopyranosyl)-3-0-benzyl-4,6-O-benzylidene-a-D-mannopyranoside 4. ... 

O-Methyl-a-L-lyxopyranosyl 0-2,6-di-deoxy-S-C-methyl-fS-D-SLVabmo-hexopyra-nosyl-( 1 - 3) -0-6-deoxy-4-0-methyl- -D-galactopyranosyl-( 1 - 4) -2,6-di-O-methyl-fi-D-mannopyranoside, 9CI, SCI... 

O-Methyl-a-L-lyxopyranosyl 4-0-(6-deoxy-4-O-methyl-p-D-galactopyranosyl) -2,6-di-O-methyl-p-D-mannopyranoside,... 

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