Synthesis of a deoxy analogue of ADP L-glycero-D-manno-heptose

Starting from L-lyxose, indium-mediated chain elongation with allyl bromide followed by acetylation and oxidative cleavage of the double bond and deprotection afforded 2-deoxy-L-galacto-heptose as a 2-deoxy analogue of the bacterial carbohydrate L-glycero-D-manno-heptose in good overall yield. For the synthesis of the ADP-activated derivative, the 2-deoxy-heptose was O-acetylated and transformed into the anomeric bromide derivative, which was then converted into the acetylated heptopyranosyl phosphate by reaction with tetrabutylammonium phosphate. Deprotection and separation of the anomeric phosphates furnished 2-deoxy-beta-L-galacto-heptopyranosyl phosphate. Coupling of the acetylated heptosyl phosphate with AMP morpholidate afforded the acetylated ADP derivative in good yield. Removal of the acetyl groups gave the target compound ADP 2-deoxy-L-galacto-heptopyranose, which may serve as substrate analogue of bacterial ADP heptosyl transferases for biochemical and crystallographic studies. (c) 2007 Elsevier Ltd. All rights reserved.