A CONVENIENT SYNTHESIS OF 4-AMINO-4-DEOXY-L-ARABINOSE AND ITS REDUCTION PRODUCT, 1,4-DIDEOXY-1,4-IMINO-L-ARABINITOL

Article abstract of DOI:10.1016/0008-6215(88)84118-1

Methyl β-D-xylopyranoside in a mixture of N,N-dimethylformamide and 2-methoxypropene containing a little hydrogen chloride gave preponderantly the 2,3-O-isopropylidene derivative, which was readily converted into its 4-trifluoromethanesulfonate.The facile displacement of the triflate group gave a 4-azido-4-deoxy-α-L-arabinopyranoside derivative, and this, on mild acid treatment, was hydrolyzed to the 2,3-diol, or under more vigorous conditions to 4-azido-4-deoxy-L-arabinose.Methyl 2,3-di-O-acetyl-4-azido-4-deoxy-α-L-arabinopyranoside, from the diol, appears (1H-n.m.r. data) to exist as an equilibrating mixture of the ⁴C₁ and ¹C₄ conformers in chloroform solution.The reduction of the azido sugar by hydrogen over Pd/C in 6M HCl yielded 4-amino-4-deoxy-L-arabinose as its hydrochloride; in 0.1M HCl, further reactions occurred to give 1,4-dideoxy-1,4-imino-L-arabinitol as the final product.The aminodeoxypentose from lipid A precursor II_A, isolated from a Salmonella mutant by Raetz et al. in 1985, was shown to be identical with the synthetic aminoarabinose by t.l.c., 1H-n.m.r. spectroscopy, and g.l.c. of the acetylated reduction products.