STEREOSELECTIVE INTRAMOLECULAR CYCLOPROPANATIONS - ENANTIOSELECTIVE SYNTHESES OF 1-ALPHA,25-DIHYDROXYVITAMIN D-3 A-RING PRECURSORS

Authors
DAUBEN WG HENDRICKS RT PANDY B WU SC ZHANG XM LUZZIO MJ
Citation
Wg. Dauben et al., STEREOSELECTIVE INTRAMOLECULAR CYCLOPROPANATIONS - ENANTIOSELECTIVE SYNTHESES OF 1-ALPHA,25-DIHYDROXYVITAMIN D-3 A-RING PRECURSORS, Tetrahedron letters, 36(14), 1995, pp. 2385-2388
Citations number
31
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
Tetrahedron letters → ACNP
ISSN journal
00404039
Volume
36
Issue
14
Year of publication
1995
Pages
2385 - 2388
Database
ISI
SICI code
0040-4039(1995)36:14<2385:SIC-ES>2.0.ZU;2-I
Abstract
Two efficient enantioselective syntheses of an A-ring precursor to 1 a lpha,25-dihydroxyvitamin D-3 have been developed. The key step in thes e sequences involves the stereoselective cyclopropanation of a chiral gamma-alkoxy-alpha-diazo-beta-keto ester. In one sequence, the 1 alpha -hydroxy group was introduced in the first step by a diastereoselectiv e ene reaction and in the other sequence by use of (S)-malic acid as s tarting material. Both routes eliminate the need for a SeO2 oxidation.