PREPARATION OF ISOBUTYL 3,4-ANHYDRO-2,6-DIDEOXY-DL-α-LYXO-HEXOPYRANOSIDE AND ITS KINETIC RESOLUTION WITH MICROSOMAL EPOXIDE HYDROLASE.

Article abstract of DOI:10.1016/0040-4020(89)80154-1

Racemic isobutyl 3,4-anhydro-2,6-dideoxy-α-lyxo-hexopyranoside, 3, was prepared starting from the cycloadduct between 3-buten-2-one and isobutyl vinyl ether, through a sequence involving hydroboration-oxidation, mesylation, anomeric equilibration, elimination and epoxidation.The intermediate isobutyl 2,3,4,6-tetradeoxy-α-3-DL-hexenopyranoside, 10 was not stable under the conditions used for its preparation (t-BuOK in DMSO), being converted in part into the corresponding 2-hexenopyranoside.Under the same conditions the α-anomer of 10 was stable.Comlete hydrolysis of DL-3 with aqueous NaOH, or with microsomial epoxide hydrolase (MEH) gave exclusively the xylo-diol (isobutyl DL-α-boivinopyranoside 5).When the hydrolylsis with MEH was stopped near 50percent conversion and the product diol was separated from the unchanged epoxide, both were optically active, the former having the L and the latter the D configuration.An ee of at least 96percent was found for both the diol and the epoxide by the use of a chiral shift reagent.