Synthesis of a novel naphthalenone endoperoxide and structural elucidation by nuclear magnetic resonance spectroscopy and theoretical calculation.
Magn Reson Chem
; 60(1): 139-147, 2022 01.
Article
em En
| MEDLINE
| ID: mdl-34265119
Sesquiterpene lactones are found in plants of Asteraceae family, and endoperoxides are known for their antimalarial activity. Structural elucidation is a relevant aspect; however, it is not uncommon to find incorrect or incomplete structural assignments in the literature. Calculations based in quantum mechanics are frequently used to compute 1 H and 13 C NMR chemical shifts, and after comparing with the experimental data, the correct structure is established from diverse candidates. Targeting the synthesis of bioactive compounds, we envisaged the synthesis of a novel endoperoxide from the natural sesquiterpene lactone α-santonin (2). Photochemical transformation of α-santonin (2) to mazdasantonin (4) followed by photooxidation catalyzed by rose bengal afforded the novel endoperoxide 5. This new endoperoxide contains five stereogenic centers and is analogous to the antimalarial agent artemisinin (1). The relative configuration of the stereogenic centers of the endoperoxide were established by nuclear magnetic resonance (NMR) analyses and confirmed by theoretical calculations. All approaches were in complete agreement, and the structure of mazdasantonin endoperoxide was established as (3S,3aS,5aS,8R,9bS)-3,6,6-trimethyl-3,3a,4,5,8,9b-hexahydro-2H-5a,8-epidioxynaphtho[1,2-b]furan-2,7(6H)-dione.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Magn Reson Chem
Assunto da revista:
QUIMICA
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Reino Unido