The invention is directed to compounds of formula (I) ##STR00001## wherein X is O or NH; R' is a hydrocarbon chain; R.sup.3 and R.sup.4 are hydrogen, OH or a monosaccharide; R.sup.5 is hydrogen or a monosaccharide; Q' is optionally present and may be a C.sub.1-10 hydrocarbon; X' is optionally present and may be O, S or NR.sup.8; and Q.sup.3 may be a hydrocarbon or hydrogen. The invention is also directed to the use of the compounds for treating cancer, infectious diseases and autoimmune diseases. The invention is also directed to syntheses of the compounds of formula (I).