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 -anomer of 10 was stable. Complete 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 hydrolysis with MEH was stopped near 50% 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 96% was found for both the diol and the epoxide by the use of a chiral shift reagent.

PREPARATION OF ISOBUTYL 3,4-ANHYDRO-2,6-DIDEOXY-DL-ALPHA-LYXO-HEXO-PYRANOSIDE AND ITS KINETIC RESOLUTION WITH MICROSOMAL EPOXIDE HYDROLASE

CATELANI, GIORGIO;
1989

Abstract

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 -anomer of 10 was stable. Complete 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 hydrolysis with MEH was stopped near 50% 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 96% was found for both the diol and the epoxide by the use of a chiral shift reagent.
Barili, Pl; Catelani, Giorgio; Catelani, G; Colonna, F; Mastrorilli, E; Paoli, M.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/10813
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