Bhupesh C. Das

A concise and general entry into (R)-4-hydroxy-2-substituted cyclopent-2-enones from D-glucose: chiral intermediates for the synthesis of PGE2, (–)-pentenomycin I, and allethrin

A general strategy for the transformation of D-glucose into different 2-substituted (R)-4- hydroxy-cyclopent-2-enones is described. This has been illustrated by the synthesis of (R)-2-[(1,3-dithian-2-yl)methyl]-4-hydroxycyclopent-2-enone, (R)-2-benzyloxymethyl-4-hydroxycyclopent-2-enone, and (R)-2-allyl-4-hydroxycyclopent-2-enone, which are potential chiral synthons for prostaglandin E2, the antibiotic (–)-pentenomycin I, and the synthetic insecticide allethrin, respectively. The second chiral synthon was obtained by two different routes, one of them involving a novel palladium(0)-catalysed rearrangement of a vinyloxirane intermediate.

Organocuprate-mediated alkylation of sugar epoxides. New stereospecific route to 3-C-alkyl-3-deoxy-α-D-glucose

The reactivity of the 5,6-anhydroglucofuranose derivatives 1 and 3, readily prepared from D-glucose, toward different cyanocuprates was examined. The former epoxide led to the corresponding C-6 chainextended sugars, e.g., 2. Alkylation of 5,6-anhydro-3-deoxy-1,2-O-isopropylidene-α-D-erythro-hex-3-enofuranose 3 with mixed cyanocuprates RCu(CN)Li [R = Me, Bu] provided a convenient and stereospecific route to 3-C-alkyl (methyl, butyl)-3-deoxy-α-D-glucofuranose derivatives 12 and 14via 1,4-addition followed by hydroboration–oxidation.

Asymmetric synthesis from pyridines: use of new chiral 1,4-dihydropyridines in a short synthesis of 5,8-disubstituted indolizidine (+)-209B

The synthetic potentiality of chiral oxazolidines, prepared from 3-picoline via a 1,4-dihydropyridine intermediate, has been illustrated by an expeditious route to the 5,8-disubstituted indolizidine alkaloid (+)-209B.