Kazakova OB, Khusnutdinova EF, Petrova AV, Yamansarov EY, Lobov AN, Fedorova AA, Suponitsky KY. Diastereoselective Synthesis of Triterpenoid 1,2,4-Trioxolanes by Griesbaum Co-ozonolysis.
JOURNAL OF NATURAL PRODUCTS 2019;
82:2550-2558. [PMID:
31490689 DOI:
10.1021/acs.jnatprod.9b00393]
[Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Diastereoselective synthesis of triterpenoid 1,2,4-trioxolanes by Griesbaum co-ozonolysis was shown for the first time. Ozonolysis of 2-methoxyoximes (syn-anti-isomers mixture) of allobetulin or methyl oleanoate with CF3-ketones resulted in asymmetrical spiro-1,2,4-trioxolanes as mixtures of diastereomers in yields up to 80-85%. The configuration of the spiro-C-2 center of individual ozonides was determined by 2D NMR spectra and X-ray crystallographic analysis. The products of ozonolysis of triterpenoid 3-methoxyoximes were mixtures of regioisomeric N-methoxylactams. Thus, the fundamental differences in the oxidation of homologous triterpenoid 2- or 3-methoxyoximes with ozone have been established. These results may afford a new stage in the development of the Griesbaum method as applied to natural compounds and biologically active peroxides.
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