Galactopyranose ring

At the end of the carbohydrate section in type O blood antigens, there is a o-galactopyranose ring to which is... 

Of course it remains that the observed Ri-value for H-l of the dideuterio derivative is still 0.110 sec" (ca. 10%) faster than that of the protio derivative and reasons for this must be sought. One possibility is that the remaining enhancement is due to the relaxation contributions emanating from the other remaining protons of the galactopyranose ring this could be checked experimentally by further deuteration experiments. 

Problem 25,13 Draw /3-o-galactopyranose and jS-D-mannopyranose in their more stable chair conformations. Label each ring substituent as either axial or equatorial. Which would you expect to be more stable, galactose or mannose ... 

Potassium hydrogen fluoride is also used to open the epoxide ring in the /1-D-galactopyranose 6 with concomitant formation of the fluoride 7.7 7... 

A characteristic feature of the dianhydrohexopyranoses is their steric rigidity. Consequently, they usually react with high and predictable regio-and stereoselectivity, mainly by diaxial cleavage of the oxirane ring. Thus, they became versatile starting materials for synthesis of various carbohydrates as well as noncarbohydrate structures. The most important compounds are l,6 3,4-dianhydro-2-0-tosyl-/l-D-galactopyranose (146), the manno epoxide 143, the altro epoxide 159, and the 2,3- and 3,4-anhydro-a//o epoxides 138 and 139. The tosyl epoxide 146 (for its crystal structure,... 

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