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Anomeric O ‐Alkylation, 9. Disaccharide Synthesis via Anomeric O ‐Alkylation
Author(s) -
Tsvetkov Yury E.,
Klotz Wolfgang,
Schmidt Richard R.
Publication year - 1992
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.199219920165
Subject(s) - chemistry , anomer , alkylation , disaccharide , toluene , alkyl , organic chemistry , base (topology) , medicinal chemistry , catalysis , mathematics , mathematical analysis
Base‐promoted reaction of tetra‐ O ‐benzyl‐glucose 1a with secondary alkyl trifluoromethanesulfonates 2 and 3 in toluene provides in the presence of 15‐crown‐5 preferentially β‐glycosides 2aβ and 3aβ , respectively, in high yields. For reactions carried out at lower temperatures and with trifluoromethanesulfonates derived from secondary hydroxy groups of sugars aprotic dipolar solvents (HMPT/DMF, HMPT/THF) are required. Thus, treatment of 1‐ O ‐unprotected hexoses 1a – e with trifluoromethanesulfonates 4 , 6 , and 7 affords the corresponding (1→4)‐connected disaccharides 4a – e and the (1→3)‐connected disaccharides 6b and 7b , respectively, in high yields. Under these conditions the α:β ratio of the products resembled the anomeric ratio of the starting material.