SYNTHESIS OF 2-DEOXY-ALPHA-D-ARABINO-HEXOPYRANOSYL AND 2-DEOXY-BETA-D-ARABINO-HEXOPYRANOSYL PHOSPHONIC-ACIDS AND RELATED-COMPOUNDS ANALOGS OF EARLY INTERMEDIATES IN THE SHIKIMATE PATHWAY

Treatment of -3,4,6-tri-O-benzyl-2-deoxy-D-arabino-hexopyranose 18 wit h trimethyl phosphite in the presence of trimethylsilyl triflate gave a separable mixture of dimethyl O-benzyl-alpha-D-arabino-hexopyranosyl )phosphonate 19 (35%) and the beta-anomer 20 (60%). The diethyl analog ue of compound 20 could be prepared stereoselectively from tributyl nz yl-2-deoxy-beta-D-arabino-hexopyranosyl)stannane 21 and diethyl chloro phosphate. Reaction of ,4,6-tetra-O-acetyl-2-deoxy-D-arabino-hexopykan ose 23 with trimethyl phosphite and trimethylsilyl triflate gave dimet hyl -2-deoxy-alpha-D-arabino-hexopyranosyl)phosphonate 25 and the beta -anomer 27 with some alpha-selectivity. Deprotection of compounds 25 a nd 27 gave the phosphonic acids 11 and 12 respectively. The esters 25 and 27 could be converted into methyl dimethoxyphosphoryl)-beta-D-arab ino-hexopyranoside 31 by free-radical bromination followed by methanol ysis, and diethyl [3,4,6-tri-O-(tert-butyldiphenylsilyl)-2-deoxy-D -ar abino-hex-1-enopyranosyl)phosphonate 33 was prepared by interaction of the 1-lithioglucal with diethyl chlorophosphate. Metallation of stann ane 21 and reaction with methyl chloroformate gave methyl hydro-4,5,7- tri-O-benzyl-3-deoxy-D-gluco-heptonate 35 which could be alkylated wit h tert-butyl bromoacetate to give, after deprotection, 3,7-anhydro-3-c arboxy-2,4-dideoxy-D-gluco-octonic acid 14.