title: Synthesis of new delta 5-7-oxygenated and delta 5,7-unsaturated brassinosteroid analogs.
abstract: We report on the synthesis of the brassinosteroid analogs (22R,23R)-3 beta, 7 beta, 22,23-tetrahydroxy-stigmast-5-ene (13), (22R,23R)-3 beta, 7 alpha, 22,23-tetrahydroxy-stigmast-5-ene (15), and (22R,23R)-3 beta, 22,23-trihydroxy-stigmast-5,7-diene (18) by means of the osmium-catalyzed asymmetric dihydroxylation of intermediate 1, available from stigmasterol. This reaction sequence produced the expected (22S,23S)- and (22R,23R)-triols 6 and 7 as well as the 22,23-diketo derivatives 2 and 3. The phytohormone activity of the new brassinosteroid analogs is discussed.
authors.affiliation: Department of Natural Products Chemistry, Institute of Plant Biochemistry, Halle/Saale, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Hellrung
authors.forename: B
authors.initials: B
authors.lastname: Voigt
authors.forename: J
authors.initials: J
authors.lastname: Schmidt
authors.forename: G
authors.initials: G
authors.lastname: Adam
mesh_terms: D010937:Plant Growth Regulators / Q000138:chemical synthesis* / Q000494:pharmacology
chemical_list: D010937:Plant Growth Regulators