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Open AccessArticle

Synthesis and Structural Determination of New Brassinosteroid 24-Nor-5α-Cholane Type Analogs

1
Departamento de Química, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso 224000, Chile
2
Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, El Llano Subercaseaux 2801, Santiago 8900000, Chile
3
Teodor Parella, Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia, Spain
*
Author to whom correspondence should be addressed.
Molecules 2019, 24(24), 4612; https://doi.org/10.3390/molecules24244612
Received: 22 November 2019 / Revised: 12 December 2019 / Accepted: 13 December 2019 / Published: 17 December 2019
(This article belongs to the Section Organic Chemistry)
Natural brassinosteroids possess a 22R, 23R configuration that appears essential for biological activity. It is, therefore, interesting to elucidate if the activity of brassinosteroids with a short side chain depends on the C22 configuration. Herein, we describe the synthesis of new brassinosteroids analogs with 24-norcholane type of side chain and R configuration at C22. The initial reaction is the dihydroxylation of a terminal olefin that leads to S/R epimers. Three different methods were tested in order to evaluate the obtained S/R ratio and the reaction yields. The results indicate that Upjohn dihydroxylation is the most selective reaction giving a 1.0:0.24 S/R ratio, whereas a Sharpless reaction leads to a mixture of 1.0:0.90 S/R with 95% yield. Using the latter mixture and following a previous reported method, benzoylated derivatives and both S and R brassinosteroids analogs were synthesized. All synthesized compounds were completely characterized by NMR spectroscopy, and HRMS of new compounds are also given. In conclusion, a synthetic route for preparation of new analogs of brassinosteroids of 24-norcholane type and R configuration at C22 were described. It is expected that this will help to elucidate if a configuration at C22 is a structural requirement for hormonal growth activity in plants. View Full-Text
Keywords: synthesis; brassinosteroid; analogues; 24-nor-5α-cholane synthesis; brassinosteroid; analogues; 24-nor-5α-cholane
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MDPI and ACS Style

Oyarce, J.; Aitken, V.; González, C.; Ferrer, K.; Olea, A.F.; Parella, T.; Espinoza Catalán, L. Synthesis and Structural Determination of New Brassinosteroid 24-Nor-5α-Cholane Type Analogs. Molecules 2019, 24, 4612.

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