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2005
Carbohydrates
Carbohydrates
U 0500
Synthesis of Acetylated Ranunculin Diastereoisomers and δ-Glucosyloxy-γ-oxo
from α or β Glucosylmethylfurfural. — The preparation of ranunculin dia28- 197 Esters
stereoisomers such as (VII) from the corresponding furanyl glucopyranosides, e.g. (V),
is achieved following different routes to precursors like (V). The best yield of (V) is
obtained via the condensation of furfuryl alcohol (I) with glucopyranosyl bromide (II)
and subsequent formylation. Photooxygenation of the furanic part of (V) and subsequent reduction afford the diastereoisomer (VII) as a mixture of epimers. This method
allows the preparation of both acetylated epimers of α- and β-ranunculin in two steps
from the corresponding anomeric furanyl glucopyranosides. In addition, selective reduction of intermediate (VI) via a hydrogen-transfer reaction, gives access to γ-keto ester (IX), a precursor of GABA derivatives possessing a glycosyl moiety. —
(COTTIER*, L.; DESCOTES, G.; SORO, Y.; J. Carbohydr. Chem. 24 (2005) 1, 55-71;
Lab. Chim. Org., CNRS, Univ. Claude Bernard Lyon, F-69622 Villeurbanne, Fr.;
Eng.) — H. Hoennerscheid
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