Galactose methylation

Galactose methyl furanoside H NMR, 4, 579 <64CC369> of-Glucose methyl furanoside H NMR, 4, 579 (64CC369)... 

Gelidium pacificum Okam. Chrondus ocellatus Holmes D-galactose D-galactose, methyl pentose, 2-keto-hexonic acid (7), sulfate, D- and irerythrose 111... 

D-galactose, methyl a- and 0-D-glucopyranosides, and a number of disaccharides, thus demonstrating that mass spectrometry is useful in the field of carbohydrate chemistry. In this study, the appearance potentials of CjHnOs ions were measured, and the results interpreted in terms of greater stability of the /9-(d or l) (equatorial) anomer with respect to the o-(d or l) (axial) one in the CA conformation. 

In like fashion, by careful stereochemical correlation of the three masked hydroxy stereocentres in 4 [i.e. C(13), C(14) and C(15) using FK506 numbering] with various monosaccharide derivatives (Scheme 17.3), Danishefsky was able to establish an appropriate chirality match with the C(2), C(3) and C(4) stereocentres of D-galactose. Methyl p-D-galactopyranoside was therefore selected as the starting material for his synthesis of 4. 

Ace tamido-2-deoxy-D-galactose Methyl 2-acetamido-2-deoxy-3-0-methyl-a-D- 31,000 200... 

Synthesis from o-galactose Methyl a-D-galactopyranoside (5) has been converted to 1-deoxygalactonojirimycin (4) (Scheme 2). Thus, methyl 2,3,4-tri-O-benzyl-... 

Hydrolysis of a trisaccharide yields two equivalents of glucose and one equivalent of galactose. Methylation, using dimethyl sulfate followed by mild acid hydrolysis, yields 3,6-di-O-methyl-D-glucose as one of the products. What features of the structure are determined by these data ... 

Write structural formulas for the a and 3 methyl pyranosides formed by reaction of o galactose with methanol in the presence of hydrogen chloride... 

The structure of compound A was established in part by converting it to known compounds Treat ment of A with excess methyl iodide in the presence of silver oxide followed by hydrolysis with dilute hydrochlonc acid gave a tnmethyl ether of D galactose Companng this trimethyl ether with known trimethyl ethers of D galactose allowed the structure of compound A to be deduced... 

Phosphate esters of 2-deoxy D-galactose (2-deoxy-D-Zt/xo-hexose) have also been obtained (15). The 6-phosphate (12) was synthesized from the methyl glycoside (9) by condensing the latter with acetone the 3,4-... 

The synthesis of halodeoxy sugars has also been achieved by reaction of sugar phosphorodiamido and phosphonamido derivatives with alkyl halides (83). Heating equimolar amounts of 6-(tetraethylphosphoro-diamido)-l,2 3,4-di-0 isopropylidene-D-galactose with methyl iodide (and benzyl bromide) at 140°C. for 4 hours afforded the 6-deoxy-6-iodo (74b) (75%) and 6-bromo-6-deoxy (74c) (56%) derivatives, respectively. 

Synthesis of Chromose A (2,6-Dideoxy-4 G-methyl-n-galactose), J. S. Brimacombe, D. Portsmouth, and M. Stacey, Chem. Ind. (London), (1964) 1758. 

Sarmentose Sedoheptulose Sedoheptulosan Solatriose 2.6- Dideoxy-3-0-methyl-D-xy/o-hexose D-a/froHept-2-ulose 2.7- Anhydro P-D-a/fro-hept-2-ulopyranose a-L-Rhamnopyranosyl-(1 ->2)-[P-D-glucopyranosyl-(1->3)]-D-galactose... 

CN, coordination number. A CN of 5-6 means that the compound contains the Sn central atom in two different environments. 1, Bu2Sn0CH2CH20 2, methyl-4,6-0-benzylidene-a-D-glucopyranoside 3, methyl-4,6-0-benzylidene-a-D-mannopyranoside 4, o-lactobionic acid 5, o-galactose 6, Bu2Sn-DNA, maleic acid. 

Deoxy-2-[ F]fluoro-D-galactose can be prepared through an addition reaction to tri-O-acetyl-D-galactal (465), but better through Sn2 reaction (K F-Kryptofix 222 in MeCN) of methyl 3,4-0-isopropylidene-2-0-triflyl-6-0-trityl-y -D-talopyranoside (220 see Section 11,2), according to the cold synthesis. 

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