Studies of enzyme-mediated reactions. Part 9. Stereochemistry of oxidative ring cleavage adjacent to nitrogen during the biosynthesis of chelidonine

Abstract

Synthetic routes are devised leading to phenethylamine derivatives which are chiral at C-1 due to ³H-substitution. These (1R)- and (1S)-amines have high configurational purity (ca. 98% one enantiomer) and their absolute configurations are confirmed by studies with the amine oxidase from pea seedlings. (6R-³H₁)-Scoulerine (37) and the (6S-³H₁)-isomer (39) are synthesised from these phenethylamines and the products are used for incorporation experiments with Chelidonium majus plants. The results for tritium retention in the two series, and for the (6RS-³H₁)-series, prove that cleavage of the bond between nitrogen and C-6 of stylopine (2) which finally leads to chelidonine (4), occurs with stereospecific loss of the hydrogen atom in Si-space.