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Synthesis of 6,6′-di-O-mycoloyl- and cornymoycoloyl-(α-d-galactopyranosyl α-d-galactopyranoside) via triflates

✍ Scribed by Avraham Liav; Mayer B. Goren

Publisher
Elsevier Science
Year
1989
Tongue
English
Weight
344 KB
Volume
51
Category
Article
ISSN
0009-3084

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✦ Synopsis

Tritylation of 2,3,2',Y-tetra-O-benzyl-(a-D-gaiactopyranosyl a-D-galactopyranoside) (4) (A. Liav, H.M. Flowers and M.B. Goren (1984) Carbohydr. Res. 133, 53--58) followed by benzylation and acid hydrolysis gave 2,3,4,2',Y,4'-hexa-O-benzyl-(a-Dgaiactopyranosyl a-D-gaiactopyranoside) ( 6). Triflation of 6 with triflic anhydride gave the ditriflate 7. Treatment of 7 with potassium mycolate or potassium corynomycolate in toluene, followed by catalytic hydrogenolysis afforded the respective cordfactor analogs 6,6'-di-O-mycoloyl-(a-D-galactopyranosyl a-D-galactopyranoside) ( 10) and 6,6'-di-O-corynomycoloyl (a-D gaiactopyranosyl a-D-gaiactopyranoside) ( 11). An alternative approach, based on the debenzylation of 2,3,2',Y-tetra-O-benzyi-6,6'-di-O-p-tolylsulfonyl-(a-D-gaiactopyranosyl a-D-gaiactopyranoside) (1) and conversion of the latter into the corresponding 3,4,Y,4'-diisopropylidene derivative 3 failed to yield satisfactory results.

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