M. Nashed, L. Anderson
Jul 1, 1977
Citations
0
Influential Citations
30
Citations
Journal
Carbohydrate Research
Abstract
Abstract The 4- O -benzoyl ( 15a ) 4- O - p -nitrobenzoyl ( 15b ) derivatives of 2,3, 6-tri- O -benzyl-1-thio- d -galactopyranose were synthesized from allyl 2,6-di- O -benzyl-α- d -galactopyranoside ( 1 ). In the first stage of the synthesis the 3-position of 1 was benzylated by an indirect route, and also by the direct reaction (preferred) of benzyl bromide with the 3,4- O -dibutylstannylene intermediate 7 . The product 6 was sequentially isomerized (allyl → 1-propenyl), acylated at the 4-position, and hydrolyzed. The free sultars 11a and 11b were converted into the thio sugars by a standard sequence involving formation of the glycosyl halides 13a and 13b and the reaction of these with appropriate sulfur nucleophiles. A third derivative ( 29 ) of 2,3,6-tri- O -benzyl-1-thio- d -galactopyranose, having a 4- O -allyl protecting group, was similarly made from the corresponding normal sugar 25 . The key intermediate 22 , precursor to 25 , was prepared by two routes from methyl 2,3,6-tri- O -benzoyl-α- d -galactopyranoside (17) .