Collect. Czech. Chem. Commun.
1998, 63, 1045-1055
https://doi.org/10.1135/cccc19981045
Structural Studies of Chelirubine and Chelilutine Free Bases
Jiří Dostála, Jiří Slavíka, Milan Potáčekb, Radek Marekc, Otakar Humpab, Vladimír Sklenářc, Jaromír Toušekd, Edmond de Hoffmanne and Raoul Rozenberge
a Department of Biochemistry, Faculty of Medicine, Masaryk University, 662 43 Brno, Czech Republic
b Department of Organic Chemistry, Faculty of Science, Masaryk University, 611 37 Brno, Czech Republic
c Laboratory of Biomolecular Structure and Dynamics, Faculty of Science, Masaryk University, 611 37 Brno, Czech Republic
d Department of Physical Chemistry, Faculty of Science, Masaryk University, 611 37 Brno, Czech Republic
e Laboratoire de Spectrometrie de Masse, Unite CICO, Departement de Chimie, Universite Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
Abstract
The structures of chelirubine and chelilutine free bases have been examined by 2D NMR spectroscopy and mass spectrometry. Chelirubine chloride (1a) upon treatment with Na2CO3 yielded free base which possessed the constitution of bis(5,6-dihydrochelirubin-6-yl) ether (2a). The free base of chelilutine (1b) was determined to be bis(5,6-dihydrochelilutin-6-yl) ether (2b). The aqueous NH3 treatment of chelilutine (1b) produced bis(5,6-dihydrochelilutin-6-yl)amine (3b). 6-Hydroxy-5,6-dihydrochelirubine (4a) and 6-hydroxy-5,6-dihydrochelilutine (4b) were detected only in CDCl3 solution by NMR spectroscopy. In CDCl3, the compound 2b underwent hydrolysis to 4b that was immediately followed by the reverse condensation to a diastereomer of 2b. Pseudokinetics of this reaction was followed by NMR spectroscopy and quantum chemical calculations were carried out to support the suggested type of molecular symmetry alteration. The known alkaloid dihydrochelirubine (5) was isolated for the first time from Sanguinaria canadensis.
Keywords: Chelirubine; Chelilutine; Quaternary benzo[c]phenanthridine alkaloids; Free bases; Pseudobases; Diastereoisomers; Dihydrochelirubine; NMR spectroscopy; Mass spectrometry; Semiempirical calculations.
