Online article for Non-subscribers

Pay per view

Heterocycles has a pay-per-view service for Non-subscribers.
You will be able to directly purchase the full text article through PayPal.
Your purchased Paper can be downloaded after the payment is completed.
An e-mail will be sent the URL to download the paper.
If you have any questions, please contact: purchase@heterocycles.com

Price: ¥ 4,400 (Yen only)
Period: This Article can be accessed for 7 days.

Paper | Regular issue | Vol 29, No. 7, 1989, pp.1343-1348
Published online, 1st January, 1970
DOI: 10.3987/COM-89-4988
On the Protonation Site of Rauwolfia Alkaloids in Highly Concentrated Sulphuric and Solutions

María A. Muñoz, Carmen Carmona, Jose Hidalgo, Manuel Balón, and Manuel López-Poveda

*Departamento de Química Física, Instituto de Ciencias de los Materiales, Universidad de Sevilla-C.S.I.C., 41012-Sevilla, Spain

Abstract

13C-Nmr spectroscopy has been used to investigate the protonation site of the Rauwolfia alkaloids yohimbine, reserpine and reserpiline in highly concentrated sulphuric acid solutions (~189M H2SO4). The chemical shifts which occur upon protonation reveal unambiguously that the alkaloids protonate on C-7, the β-position with respect to their indole ring, and suggest that the indoleninium cations of the methoxy-substituted alkaloids have principally an enamine structure.