Tetrahydropalmatine products

Spath and Kruta have also prepared dZ-tetrahydropalmatine by the process described for meso- and r-corydalines (p. 289), and by condensing tetrahydropapaveroline with formaldehyde and methylating the product, obtained in poor yield, a mixture of tetrahydropalmatine and ftorcoralydine. 

Labeled muramine (395) was synthesized for biosynthetic studies from tetrahydropalmatine (27) in 35% overall yield via the von Braun reaction product 30c (Section II,A,2) and the alcohol 403 (Scheme 76) (42). Labeled 13-oxygenated muramines 405a and 405b were obtained by oxidation of dihydropalmatine metho salt (404) with osmium tetroxide (42). 

The yield of the lithiation, in case of benzylamine, is again good only when the amine is tertiary. This then leads to the quaternary salt in the cyclisation reaction. The dehydrogenation of quaternary salt does not proceed in synthetically useful yield. For this reason the method is not suitable for the synthesis of isoquinolines themselves. However, when the desired product is a tetrahydroisoquinoline the method can be of some value as in a synthesis of tetrahydropalmatine (vide infra). 

An alkaloid, shobakunine, isolated from Mahonia philippinensis (134) and Archangelisia flava (152), was shown to be a mixture, possibly molecular, of berberine and palmatine, and its reduction product, tetrahydro-shobakunine, was either a compound or mixture of dZ-canadine and of dl-tetrahydropalmatine. 

Still another synthesis was achieved by Spath and Kruta (227), who showed that tetrahydropapaveroline (XXXI) on condensation with formaldehyde yielded two products which on complete 0-methylation gave a separable mixture of tetrahydropalmatine (XXXII) and norcoralydine (analogous to XXVII). It is to be noted that in the former case the condensation took place in a position ortho to a hydroxyl group. In the latter... 

Auroterisine on methylation with diazomethane yielded a mixture from which dZ-tetrahydropalmatine was readily separated in a pure form. The diethyl ether on ethylation and oxidation yielded the same products which were obtained from scoulerine (233). 

Furthermore, corydaline, like tetrahydropalmatine, has four methoxyls, but its formula contains CH2 more, which indicates that it should be a C-methyl derivative of the latter. The final products of its oxidation by permanganate are hemipinic and m-hemipinic acid, and it is possible to isolate, along with a number of other products, the compound called coryd-aldine (LIII) (246), the structure of which has been adequately proved by... 

Parallel to the conversion of canadine to allocryptopine and its cyanogen bromide cleavage product (discussed in Secs. 23.1 and 23.2), tetrahydropalmatine was converted to the A -metho salt 7 which was hydrogenolyzed to the keto amine 8. Subsequent cyanogen bromide cleavage, succeeded by alkaline ethanol-ysis furnished the dibenzocyclopentazepine 4 ... 

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