[Synthesis of secasterol and 24-episecasterol and their toxicity in MCF-7 cells].

A convergent synthesis of biosynthetic precursors of brassinosteroids - secasterol and 24-episecasterol with Δ²-bond in cycle A is described. The key stages in the construction of the side chain of these compounds were Julia olefination of steroid 22-aldehyde followed by asymmetric Sharpless dihydroxylation of the intermediate Δ²²-olefin. Toxicity of synthesized compounds against breast carcinoma MCF-7 cells was studied.

[Synthesis of brassinolide and its biosynthetic precursors using methyl-3-hydroxy-2-methylpropionate].

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.