Stereoselective synthesis of the alpha-allyl C-glycoside of 3-deoxy-D-manno-2-octulosonic acid (KDO) by use of radical chemistry.

ABSTRACT

Methyl 2-C-allyl-2,6-anhydro-3-deoxy-4,57,8-di-O-isopropylidene-D-glycero- D-talo-octonate (9a), the protected alpha-allyl C-glycoside of 3-deoxy-D-manno-2-octulosonic acid (KDO), has been synthesized using a photochemically initiated radical reaction. A phenyl thioglycoside (8) was used as the substrate and allyltributyltin as the acceptor. The stereoselectivity of the reaction was 9010 in favour of the talo-isomer (alpha-).