Stereochemistry of 13-Hydroxyprotoberberines, Their Derivatives, and a Protopine-Type Alkaloid

Article abstract of DOI:10.1021/jo00143a021

13C NMR and 1H NMR spectral analyses have been used to establish the conformational structure of ophiocarpine (1), epiophiocarpine (2), their acetates and corresponding N-quaternary salts, and allocryptopine (5).