Auto-oxidation of Ent-beyer-15-en-19-al isolated from the essential oil of the heartwood of Erythroxylum monogynum Roxb.: formation of 15,16-epoxy-ent-beyeran-19-oic acid and other products

Autor: K. Tuley Dayananda De Silva, T. M. Samantha Gome Tennakoon, C. Padumadasa, A.M. Abeysekera, G. M. Kamal B. Gunaherath, D. Siril Abeywickrama Wijesundara
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: BMC Chemistry, Vol 14, Iss 1, Pp 1-12 (2020)
DOI: 10.1186/s13065-020-00671-9
Popis: Chemical investigation of the essential oil obtained from the heartwood of Erythroxylum monogynum Roxb. yielded three beyerene type diterpenoids ent-beyer-15-ene (1), ent-beyer-15-en-19-ol (erythroxylol A) (2) and ent-beyer-15-en-19-al (3). Ent-beyer-15-en-19-al (3) was found to be unstable at room temperature, giving rise to hitherto unknown 15,16-epoxy-ent-beyeran-19-oic acid (4). This conversion involves the auto-oxidation of a C-4 axial aldehyde group of an ent-beyer-15-ene diterpenoid with the concurrent epoxidation of the C-15 double bond. This is the first report of the auto-oxidation of an aldehyde group to a carboxylic acid group with the concurrent epoxidation of a double bond in the same compound. Further investigation of this observation under controlled conditions resulted in the isolation and identification of ent-beyer-15-en-19-oic acid (5), two new epoxy hydroperoxides, 15,16-epoxy-19-nor-ent-beyeran-4α-hydroperoxide (6a), 15,16-epoxy-18-nor-ent-beyeran-4β-hydroperoxide (6b), and two new hydroperoxides, ent-beyer-19-nor-15-en-4α-hydroperoxide (7), ent-beyer-18-nor-15-en-4β-hydroperoxide (8) and ent-beyer-18-nor-15-en-4β-ol (9). Identification of these compounds was carried out by the extensive usage of spectroscopic data including 1D and 2D NMR. The acid 5 and the alcohol 9 have been reported previously as natural products from Elaeoselinum asclepium and Erythroxylum monogynum. The mechanistic basis of this auto-oxidation reaction is discussed.
Databáze: OpenAIRE
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