Glucosamine 유도체의 입체선택적 합성(IV): 베타-아노머의 벤질화 반응

Abstract

N-Benzylamino-β-D-glucopyranose derivatives 4 were synthesized from anomeric mixture of glucosamine 1, which is a monomerhydrochloride 1 with phenylaldehyde derivatives afforded the corresponding N-benzyilidene-β-D-glucopyranoses 2 in 45-88% yield.Second, these were subjected with acetic anhydride to give tetraacetoxybenzyildene-β-D-glucopyranose 3 of which the four hydroxygroup were acetylated and the stereochemistry of acetoxy group substituted to anomeric carbon was equatorial, β isomer. Third, thereaction of imine intermediate 3 with sodium borohydride in a solution of acetic acid and methanol resulted in N-benzylamino-β-D-glucopyranose 4 in 21-51% yield through reductive benzylation. By the same method 7 derivatives 4 in which electron donating groupor halogen atom is substituted in ortho, meta and para of the phenyl moiety were synthesized. The pyranose ring and the acetoxyprotecting group were intact in reductive benzylation. The structure of the synthesized compounds were elucidated through 1H NMRspectra and high resolution mass spectroscopy. The most of the intermediates 3 were solid phase and the final target compounds wereoily liquid. In the 1H NMR of the N-benzylamino-β-D-glucopyranose 4, the H-1 proton showed at 5.5 ppm with coupling constant(J)of 6.3-8.5 Hz, and methylene protons showed at 3.7 ppm with J of 13-14 Hz as a AB splitting pattern.