Mannich reaction of 1 -(2-bromo-5-hydroxy-4-methoxybenzyl) -1;2,3,4-tetrahydro-6 7-methylenedioxyisoquinoline (1x1 gave 12-bromonandinine (11) which was debrominated to afford (i)-nandinine (I). Methylation of (i)-nandinine with diazomethane gave (i) -canadine (111). dehydrogenation of which with iodine afforded berberine iodide (XI). NANDININE (I), C&,,NO,, and canadine (III), C20H21N0,, have been isolated from Nandirta domestics and CorydaZis 3 species, respectively. Their structures were elucidated from degradative evidence and by total synthesis.** We are investigating a modified Mannich reaction which selectively affords protoberberines cyclised ortho to the hydroxy group. This reaction has been

The 270 MHz 'H n.m.r. spectra of some model tetrahydroprotoberberines have been analysed and the dependence of the chemical shifts and the geminal and interbenzylic coupling constants on the conformation examined. Their use for conformational analysis was illustrated on two 8-methyl substituted epimers.

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