Synthesis of a Prenylated and Immunosuppressive Marine Galactosphingolipid with Cyclopropane-Containing Alkyl Chains: (2S,3R,11S,12R,2′′′R,5′′′Z,11′′′S,12′′′R)-Plakoside A and Its (2S,3R,11R,12S,2′′′R,5′′′Z,11′′′R,12′′′S) Isomer

Abstract

Plakoside A (1) {(2S,3R,11R*,12S*)-2-[(2′′′R,5′′′Z,11′′′R*, 12′′′S*)-2′′′-hydroxy-11′′′,12′′′-methylene-5′′′-docosenamido]-1-O-[2′-O-(3′′-methyl-2′′-butenyl)-β-D-galactopyranosyl]-11,12-methylene-1,3-docosanediol} is a prenylated galactosphingolipid isolated as an immunosuppressant from the marine sponge Plakortis simplex. (2S,3R,11S,12R,2′′′R,5′′′Z,11′′′S,12′′′R)-Plakoside A (1) has been synthesized by combining the sphingosine part 16, the α-hydroxy acid part 28, and the prenylated sugar part 33. (2S,3R,11R,12S,2′′′R,5′′′Z,11′′′R,12′′′S)-Plakoside A (1′) has also been synthesized.