title: [Synthesis of brassinolide and its biosynthetic precursors using methyl-3-hydroxy-2-methylpropionate].
abstract: Formal synthesis of plant hormones that belong to the group of 24alpha-methylbrassinosteroids, including brassinolide and its biosynthetic precursors with one hydroxyl group in their side chain, was performed. Stereochemistry of a methyl group at the C24 atom was provided by the choice of the desired enanthiomer of methyl-3-hydroxy-2-methylpropionate and by the sequence of its conversions into the chiral intermediate that was necessary for the formation of the C23-C28 fragment of the side chain. The (22R,23R)-diol group was introduced by the Sharpless asymmetric dihydroxylation of the intermediate delta22-steroids, the products of consecutive reactions of attachment of a low-molecular sulfone to the steroid C22-aldehyde, acetylation, and reductive desulfurization of the intermediate beta-acetoxysulfones. Reduction of 22-acetoxy-23,25-disulfones was shown to proceed with the preservation of the functional group at atom C22.
authors.forename: V A
authors.initials: VA
authors.lastname: Khripach
authors.forename: V N
authors.initials: VN
authors.lastname: Zhabinskiĭ
authors.forename: K V
authors.initials: KV
authors.lastname: Parkhimovich
authors.forename: O V
authors.initials: OV
authors.lastname: Gyliakevich
mesh_terms: D060406:Brassinosteroids; D002777:Cholestanols / Q000138:chemical synthesis* / Q000737:chemistry*; D010937:Plant Growth Regulators / Q000138:chemical synthesis* / Q000737:chemistry*; D013260:Steroids, Heterocyclic / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D060406:Brassinosteroids; D002777:Cholestanols; D010937:Plant Growth Regulators; D013260:Steroids, Heterocyclic; C023623:brassinolide