Hirotoshi Numata

A new route to substituted 3-methoxycarbonyldihydropyrans; enantioselective synthesis of (–)-methyl elenolate

A stereoselective chiral synthesis of (–)-methyl elenolate has been achieved by employing a newly developed method for the construction of substituted 3-methoxycarbonyldihydropyrans based on a radical cyclisation reaction.

Total synthesis of (+)-brefeldin C via Lewis acid mediated cyclization of an epoxy-allylsilane

Abstract An enantioselective synthesis of (+)-brefeldin C has been achieved using Lewis acid mediated cyclization of a chiral epoxy-allylsilane as a key step.

A new synthesis of a steroid side chain via stereocontrolled protonation: synthesis of (–)-desmosterol

Protonation of the lactone enolate (9), obtained from the 20-cyano-steroid (3) and (R)-benzyl 2,3-epoxypropyl ether (6), with saturated aqueous sodium sulphate proceeds in a highly steroselective manner from the less hindered side to give the (20R)-lactone (10) which can be converted into the (20R)-steroid, desmosterol (17).

A novel stereoselective synthesis of a chiral key intermediate for the preparation of vitamin D3

Abstract The cyclopentanone 3a, a key intermediate in the synthesis of vitamin D3 and its metabolites, has been prepared in optical active form using(S)-γ-trityloxymethyl-γ-butyrolactone (6) as a chiral building block.

Silicon-mediated isoquinoline alkaloid synthesis: novel route to (±)-xylopinine and (±)-laudanosine

A novel synthesis of the isoquinoline alkaloids, (±)-xylopinine and (±)-laudanosine, has been developed via intra- and molecular nucleophilic addition, respectively, of an organosilicon compound to a carbon–nitrogen double bond.

Enantioselective synthesis of a C/D-ring synthon for the preparation of vitamin D3 metabolites

The hydrindanol (2), a C/D-ring synthon of vitamin D3 metabolites, has been synthesized enantioselectively by the use of stereoselective epoxy alcohol-initiated polyalkene cyclisation as a key step.