F. R. Seymour
Oct 1, 1973
Citations
0
Influential Citations
5
Citations
Journal
Carbohydrate Research
Abstract
Abstract The synthesis of the 4-methyl, the 2,4-dimethyl, and the 2,3,6-trimethyl ethers of methyl α- D -mannopyranoside has been accomplished by the use of selective, benzoyl protecting groups, the 1-ethoxyethyl protecting group, and methylation with diazomethane. Considerable differences were noted in the i.r.- and n.m.r.-spectroscopic and t.l.c. properties of the diastereoisomers of methyl 4-O-[1-ethoxyethyl]-α- D -mannopyranoside. A structure, analogous to that of trans-decalin, maintained by intramolecular hydrogen-bonding is proposed for these compounds. The differences in physical properties of the two diastereoisomers are interpreted on the basis that the (R) isomer has an axially attached methyl group, and, therefore, the ring involved cannot be so stable as that of the (S) isomer.