Molecular recognition IX. The synthesis of the H-type 2 human blood group determinant and congeners modified at the 6-position of the N-acetylglucosamine unit

The synthesis of the methyl glycosides of the H-type 2 human blood group determinant (α- L -Fuc-(1c → 2b)-β- D -Gal-(1b → 4a)-β- D -GlcNAc-OMe) and its 6a-deoxy, 6a-O-methyl, 6a-chloro-6a-deoxy, 6a-deoxy-6a-fluoro, 6a-amino-6a-deoxy, 6a-acetamido-6a-deoxy, and 6a-deoxy-6a-pivalamido congeners is reported. The compounds were prepared to test the hypothesis that the binding of the H-type 2 trisaccharide by the lectin I of Ulexeuropaeus requires OH-6a to become intramolecularly hydrogen bonded to the neighboring O-5a ring atom. The results obtained in the binding studies are reported in an accompanying publication (Spohr, Paszkiewicz-Hnatiw, Morishima, and Lemieux) where it is demonstrated that the formation of the intramolecular hydrogen bond is not required for effective binding. In view of the results reported in another accompanying paper (Nikrad, Beierbeck, and Lemieux), OH-6a most likely remains in contact with the aqueous phase near the periphery of the combining site. Keywords: N-acetylglucosamine derivatives, H-type 2 blood group determinant and congeners, oligosaccharide synthesis.