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1. A process for synthesizing a lipochitooligosaccharide compound having the structure:where R1 is selected from: H, and C1 to C20 alkyl, aryl, and aralkyl; R2 and R3 are independently C1 to C20 alkyl, aryl, aralkyl, C2 to C20 mono, di or polyalkenyl groups, or C2 to C20 mono, di or polyalkynyl, groups; and n is from 0 to about 20;comprising:
a) providing a compound of structure D wherein R1 is H, C1 to C20 alkyl, aryl, or aralkyl; b) removing the ester groups and the N-phthalimido groups of non-silylated sugar unit of the compound of structure D by first removing the ester groups by transesterification and second removing N-phthalimido groups using an ethylenediamine Merrifield resin to form an amino-sugar product; c) selectively reacting the amino groups on the non-silylated sugar units of the amino-sugar product of b) with an acylating reagent to make an N-acyl derivative product; d) removing the silyl group on the silylated sugar unit of the N-acyl derivative product of c) by reacting the N-acyl derivative product with tetra-N-alkyl ammonium fluoride to produce a de-silylated product; e) removing the ester and the N-phthalimido group of the de-silylated product of d) by reacting the de-silylated product with an ethylenediamine Merrifield resin under refluxing conditions to produce a de-N-phthalimidated product; f) acylating the terminal amino group of the de-N-phthalimidated product of (e) with fatty acids activated with carbodiimide and N-hydroxylbenztriazole, or an acid halide of the formula R1COX, in the presence of a base catalyst,
where X is a halide, and R1 is selected from C1 to C20 alkyl, aryl, aralkyl, mono, di or polyalkenyl, or mono, di or polyalkynyl groups; to form the lipochitooligosaccharide; and g) isolating the lipochitooligosaccharide. |
