THE STRUCTURE, ABSOLUTE CONFIGURATION AND BIOSYNTHESIS OF NORTILIACORININE A

Article abstract of DOI:10.1016/S0040-4020(01)98971-9

The incorporation of (+/-)-norcoclaurine, (+/-)-coclaurine, (+/-)-N-methylcoclaurine and dehydro-N-methylcoclaurine into nortiliacorinine A in Tilicora racemosa colebr has been studied and specific utilisation of the (+/-)-coclaurine demonstrated.The evidence supports oxidative dimerization of two coclaurine units to give nortiliacorinine A.Experiments with (+/-)-N-methylcoclaurine and (+/-)-<1-3H, N-14CH3>N-methylcoclaurine established that only one N-methylcoclaurine unit is specifically utilised to constitute that the H atom at the asymmetric centre in the 1-benzylisoquinoline precursor is retained in the bioconversion into nortiliacorine A.Double labelling experiment with (+/-)-<1-3H,6,0-14CH3>N-methylcoclaurine showed that O-Me function of the precursor is lost in the bioconversion into nortiliacorine A.Parallel feedings of (+)-(S)-, and (-)-(R)-N-methyl-coclaurines and (-)-(S)-, and (+)-(R)-coclaurines revealed that the stereo-specificity is maintained in the biosynthesis of nortiliacorinine A from 1-benzylisoquinoline precursors and established S,S'-configuration at the two asymmetric centres in nortiliacorinine A.