
%0 Journal Article
%A Taylor, C. M. 
%A Weir, C. A. 
%A Jørgensen, C. G. 
%T Synthesis of <font size="-2">D</font>-Galactopyranosides of <emph type="2">trans</emph>-4-Hydroxy-<font size="-2">L</font>-proline Utilizing the Sulfoxide Glycosylation Method
%J Australian Journal of Chemistry
%D 2002/06/04
%V 55
%N 2
%P 135-140
%K 
%R https://doi.org/10.1071/CH01156
%U https://www.publish.csiro.au/paper/CH01156 
%X Phenyl 1-thio-&#946;-D-galactopyranoside (1) was converted into two sulfoxide glycosyl donors: phenyl (2,3,4,6-tetra-O-benzyl)-1-thio-&#946;-D-galactopyranoside S-oxide (3) and phenyl (2,3,4,6-tetra-O-pivaloyl)- 1-thio-&#946;-D-galactopyranoside S-oxide (5). These glycosyl donors were then each reacted with Na- fluorenylmethoxycarbonyl-trans-4-hydroxy-L-proline allyl ester (7). The glycosylation reactions were conducted at -70&#176;C with triflic anhydride as promotor, in the presence of 2,6-di-tert-butyl-4-methylpyridine. In the case of the perbenzylated sulfoxide donor (3), the major product was Na-fluorenylmethoxycarbonyl-trans-4-hydroxy- 4-O-[(2,3,4,6-tetra-O-benzyl)-a-D-galactopyranosyl]-L-proline allyl ester (8a). In dichloromethane, the a-to-&#946; ratio was 3 : 1 and in toluene this improved to 5 : 1, with a combined yield of 41%. In the case of the perpivaloylated sulfoxide donor (5), Na-fluorenylmethoxycarbonyl-trans-4-hydroxy-4-O-[(2,3,4,6-tetra-O-pivaloyl)-&#946;-D- galactopyranosyl]-L-proline allyl ester (9) was obtained as the sole glycoside product in 46% yield. 
