TCP BUILDING-BLOCKS FOR OLIGOSACCHARIDE SYNTHESIS - PROGRESS TOWARDS THE SYNTHESIS OF NODULATION FACTORS

The ability of tetrachlorophthaloyl (TCP) sugars to act as glycosyl ac cepters as well as the viability of TCP as a global amine protecting g roup in the synthesis of polyglucosamine natural products such as N-me thyl-N-lipid nodulation factors have been examined. Disaccharides corr esponding to the reducing end segments and the core region of the targ et nodulation factors were assembled from n-pentenyl glycosides. TCP a ccepters were successfully coupled with a variety of pentenyl glycosyl donors to produce beta-(1-->4) oligosaccharides in good yields. Model coupling reactions to produce trisaccharides provided clear evidence for the disarming effect of an ester at O3 on a C4-OH in the glycosyl acceptor. Also, a unique pentenyl donor, which contained the desired N -methyl-N-lipid moiety for the non-reducing end segments of the target compounds, was synthesized and its efficacy in a coupling reaction wa s tested.