Synthesis of 2,3,4,6-Tetra-O-Acetyl-1,5-Anhydro-D-lyxo-Hex-1-enitol and its Conversion into a Hex-3-enopyranosid-2-ulose Analogue of Levoglucosenone

MANZANO, V. E.; REPETTO, E; UHRIG, M. L..; VARELA, O.

Carhydrate Chemistry: Proven Methods

Taylor & Francis

Año: 2009;

The alfa,beta–unsaturated carbonyl group is found in a large number of natural and synthetic products. This functionality is commonly related to a wide range of biological activities, such as antitumor, antiviral, antimicrobial, and gastric antiulcer activities. Particularly, sugar enones have become important synthetic targets not only due to their bioactivity but also for their use as building blocks in the synthesis of varied targets. The usefulness of sugar enones as chiral building blocks relies upon the fact that they posses olefinic and carbonyl unsaturations to which a number of well−established reactions may be applied. In addition, because of the chiral environment generated by the remaining stereocenters, reactions applied to the enone system are usually highly diastereoselective. We describe herein a straightforward and high yielding synthesis of benzyl 3,4-dideoxy-alfa-D-glycero-hex-3-enopyranosid-2-ulose from D-galactose, via the 2,3,4,6-tetra-O-acetyl-1,5-anhydro-D-lyxo-hex-1-enitol. A convenient preparation of this intermediate is also described, as glycal derivatives themselves are useful chiral synthons. Glycal 3 has been prepared in low yield a long time ago, and it has been determined that in the crystalline state adopts the 4H5 half-chair conformation.as glycal derivatives themselves are useful chiral synthons.