THE BIOSYNTHESIS OF THE ALKALOIDS OF CROTON SPARSIFLORUS MORONG

Article abstract of DOI:10.1016/S0040-4020(01)98851-9

Incorporation of tyrosine, dopa, dopamine, 4-hydroxyphenylpyruvic acid, (+/-)-, norcoclaurine-1-carboxylic acid, -norcoclaurine, -coclaurine, and -N-methylcoclaurine into N-methylcrotsparine, N-methylcrotsparinine and N-methylsparsiflorine in Croton sparsiflorus Morong has been studied.The evidence supports the direct oxidative coupling of (+)-, and (-)-N-methylcoclaurines to give N-methylcrotsparine and N-methylcrotsparinine, respectively.Tracer experiment show that N-methylcrotsparine undergoes dienone-phenol rearrangement to give N-methylsparsiflorine.A doublelabelling experiment with (+/-)-N<14C>methyl<1-3H>coclaurine demonstrated that the H atom at the asymmetric centre in the 1-benzylisoquinoline precursor is retained in the bioconversion.The intermediacy of norcoclaurine-1-carboxylic acid and specific incorporation of dehydro-N-methylcoclaurinium salt into the bases have been demonstrated.