The title compound was prepared by two related methods. Norspermidine 1,7-diamide (I) was acylated at the free amino group with N-(benzyloxycarbonyl)-D-threonine (II), yielding triamide (III). The benzyloxycarbonyl protecting group of (III) was then removed by treatment with PdCl2 to give amine (IV). Subsequent methyl ether cleavage to produce the phenolic derivative (V) was carried out using BBr3 in cold CH2Cl2. Then, cyclization of the amino alcohol moiety of threonine derivative (V) with ethyl 2,3-dihydroxybenzimidate (VI) provided the target oxazoline.

In an alternative method, 2,3-bis(benzyloxy)benzoic acid (VII) was activated as the corresponding imidazolide (VIII) prior to condensation with norspermidine (IX). The resulting diamide (X) was further acylated with N-(benzyloxycarbonyl)-D-threonine (II) to afford triamide (XI). Hydrogenolysis of the O-benzyl and N-benzyloxycarbonyl protecting groups of (XI) then gave amino alcohol (V), which was finally cyclized with imidate (VI) as above.

In an alternative method, 2,3-bis(benzyloxy)benzoic acid (VII) was activated as the corresponding imidazolide (VIII) prior to condensation with norspermidine (IX). The resulting diamide (X) was further acylated with N-(benzyloxycarbonyl)-D-threonine (II) to afford triamide (XI). Hydrogenolysis of the O-benzyl and N-benzyloxycarbonyl protecting groups of (XI) then gave amino alcohol (V), which was finally cyclized with imidate (VI) as above.