Synthesis of Helicobacter pylori lipid A and its analogue using p-(trifluoromethyl)benzyl protecting group

Synthesis of lipid A 1 isolated from Helicobacter pylori strain 206-1 has been achieved in 2.2% total yield through 14 steps from d-glucosamine by employing a p-(trifluoromethyl)benzyl group for protection of the hydroxy group on the 3-hydroxy fatty acid residue. The synthetic specimen was identical with the natural counterpart in chromatographic, spectroscopic, and biological aspects. A structural analogue 2 which lacks the ethanolamine residue of 1 was also synthesized, and 2 was found to exhibit less potent IL-1β-inducing activity than 1.