Galactopyranoside methyl 3,4-anhydro

Galactopyranoside, methyl a-D-benzoylation of, 250 sulfonylation of, 247 —, methyl /3-D-, sulfonylation of, 248 —, methyl 3,6-anhydro-2,4-di-0-methyl-jS-D-, 270... 

Methyl 3,6-anhydro-a-D-galactopyranoside to Methyl 3,6-anhydro-a-D-glucopyranoside... 

The product retains, however, the configuration of D-galactose and is in fact methyl trimethyl-D-galactopyranoside (LII). The intermediate formation of a 1,3-anhydro ring is postulated. 

Anhydro-trimethyl-D- Methyl 3,6-anhydro-/9-r>-glucose dimethyl acetal (R=Me) galactopyranoside... 

Anhydro-D-dulcitol (XXXV) has been prepared by a method which demonstrates its structure. Hockett and coworkers11 prepared it from methyl 3,6-anhydro-a-D-galactopyranoside but both the anhydride itself and its tetraacetate were liquid. Carr63 obtained another anhydro derivative of dulcitol by heating it with phosphoric acid. This also was a liquid but gave rise to a crystalline dibenzoate and a dicarbanilate and was a dianhydro derivative, but no constitutional studies have yet been carried out on this substance. 

With sodium hydroxide, methyl 2,3-anhydro-a-D-allopyranoside yields methyl 3,6-anhydro-a-D-glucopyranoside by intramolecular attack on the epoxide ring by the 6-hydroxyl group.72 Methyl 2,3-anhydro-a-D-gulopyranoside behaves similarly, and its intermediacy accounts for the conversion of methyl 3,4-anhydro-a-D-galactopyrano-side into methyl 3,6-anhydro-a-D-galactopyranoside on treatment with alkali.67... 

On deamination, 2-amino-l,5-anhydro-2-deoxy-l>mannitol gave l,5-anhydro-2-deoxy-D-eryf/iro-3-hexulose as the major product.54 The substitution product 1,5-anhydro-D-glucitol was formed to a small extent, and inversion again predominated, as with other axial amines (60, 72, and methyl 4-amino-4-deoxy-a-D-galactopyranoside) this is in accord with the predominant inversion of configuration reported for deamination, in water-rich media, of simple cyclohexyla-mines,154 and aminodecahydronaphthalenes39 in which the amino group is axial. As discussed previously (see p. 15), the extent of inversion can vary considerably with the nature of the solvent, and steric factors appear to be important in deaminations of per-O-acetyl amines (see pp. 37 and 49). 

Imidazole-l-sulfonyl esters of a-D-galactopyranoside derivatives are easily transformed to their corresponding 3,6-anhydro derivatives [78] at room temperature in dry DMF, by intramolecular participation of 3-O-methyl substituent (Scheme 16). Formation of... 

J. Jary and K. Capek, Amino sugars. 5. Preparation of methyl-3,4-anhydro-6-deoxy-a-D-galactopyranoside derivatives, Collect. Czech. Chem. Commun., 31 (1966) 315-320. 

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