Synthesis of a prenylated and immunosuppressive marine galactosphingolipidwith 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

Plakoside A (1) {(2S,3R,11R*,12S*)-2-[(2'''R,5'''Z,11'''R*, 12'''S*)-2"'-hy droxy-11"',12"'-methylene-5"'-docosenamido] -1-O-[2'-O-(3"-methyl-2"-buteny l)-beta -D-galactopyranosyl]-11,12-methylene-1,3 -docosanediol} is a prenyl ated galactosphingolipid isolated as an immunosuppressant from the marine s ponge Plakortis simplex. (2S,3R,11S,12R,2'''R,5'''Z,11'''S,12'''R)-Plakosid e A (1) has been synthesized by combining the sphingosine part 16, the alph a -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.