N-Methylputrescine Oxidation during Cocaine Biosynthesis: Study of Prochiral Methylene Hydrogen Discrimination Using the Remote Isotope Method†
journal contributionposted on 15.12.1999, 00:00 by Thomas R. Hoye, Jeffrey A. Bjorklund, Dmitry O. Koltun, Matthew K. Renner
The stereoselectivity of N-methylputrescine (3) oxidation to pyrrolinium ion 4 in Erythroxylum coca during cocaine (1) biosynthesis was studied. The remote isotope method was used to advantage. Each enantiomer of 4-monodeuterated N-methylputrescine served as a precursor for plant feeding. To facilitate mass-spectrometric analysis of products, a 2H313C-methyl group was also incorporated into the 4-deuterio-N-methylputrescines. Oxidative deamination of N-methylputrescine was found to be stereoselective; the pro-S hydrogen atom is removed with 6−10:1 selectivity.