For some tumors, a protective anti-tumor immune response can be initiated by marking tumor cells for opsonization by coating them with antibodies. Naturally occurring anticarbohydrate antibodies specific for L-rhamnose are abundant within human serum. This discovery has created an interest in chemically synthesizing an a-L-RhaCer glycolipid that can insert into the membrane of a tumor cell and potentiate an anti-tumor response mediated through anti-L-rhamnose antibodies. To complete the synthesis the acceptors desired for glycosylation, 3-O-benzoylazidosphingosine or 3-O-alloxycarbonylsphingosine, were prepared from D-xylose. The thioglycoside donor, 2,3,4-tri-O-acetyl-1-(4-tolyl)thio-a-L-rhamnopyranoside, and the trichloroacetimidate donor, 2,3,4-tri-O-acety-1-(2,2,2-trichloroethanimidate)-a-L-rhamnopyranoside, were synthesized in 50% and 78% yield overall, respectively. With key intermediates in hand, progess toward the synthesis of an a-L-RhaCer glycolipid will be reported.

Synthesis of α-L-rhamnosylceramides

244th National Meeting (2012)

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