Two new tetrahydroprotoberberine alkaloids are reported, one from Corydalis thalictrifolia and the other from Corydalis tlrberosa. The former is apparently identical with a previously described synthetic compound. The latter is a des-methyl derivative of the first. Both compounds are 13-methyltetrahydroprotoberberines in which the hydrogens at C-13 and -14 are cis to one another. An examination has been made of the p.m.r. spectra of the two new bases and of several 13-methyltetrahydroprotoberberines of established structure and stereochemistry. The spectra can be used to assign the relative stereochemistry of these 13-methyl compounds.Canadian Journal of Chemistry, 48, 3673 (1970) From Coryhlis rhalictrifolia Franch. (1) and from Coryrlalis tuberosa D C (C. Cava (L.) Schweigg. et. Korte) (2) a number of tetrahydroprotoberberines and several 13-methyltetrahydroprotoberberines have been isolated along with alkaloids of other isoquinoline systems. We report here the isolation and structure of two new alkaloids, one from each of these species, which are tetrahydroprotoberberines with 13-methyl groups. In the course of this investigation we examined the p.m.r. spectra of many of the known 13-methyltetrahydroprotoberberines. From this work it is evident that p.m.r. can be used to assign the relative configuration at C-13 but had absorption in the 2700-2800 cm-' region. The mass spectrum of cavidine has a molecular ion at mle 353 (35) and fragment ions at n7/e 338 (7.9, 192 (5.5), 190 (4.5), and 162 (loo).' This fragmentation pattern can be rationalized, Scheme 1, on the basis of structure 1 for cavidine (3) but the mass spectrum does not define the substitution pattern. The p.m.r. spectrum confirmed the nature of the substituent groups and enabled them to be assigned to the positions shown in structure 1.The 100 MHz p.m.r. spectrum of 1 in CDCl, is shown in Fig. 1. The presence of ~'cH-CH, / and -14 in this series of alkaloids.group is apparent from the signal centered at The first of the two new alkaloids, C2,H2,N0,, 0.98 6, J = 7 Hz, and the presence of two from C. thalictrifolia, was assigned the trivial methoxyl groups and of one methylenedioxy name, cavidine, 1. The base was optically inac-group by the signals at 3.88 (area 6) and 5.93 tive, melted at 192" and had h,,,,(MeOH) 285 (area 2), respectively. The presence of four mp in its u.v. spectrum. The i.r. spectrum showed protons in the aromatic region is established by the absence of carbonyl or hydroxyl absorption integration but the spectrum in the aromatic 'Intensities are given in parentheses. For personal use only.
