Geissoschizine methyl ether

Cryptopine-type indole alkaloid bumamicine (572) has been synthesized from geissoschizine methyl ether (31) (287). In the first step, geissoschizol (34) was prepared, and then cleavage of the C/D ring fusion was carried out by means of ethyl chloroformate. Finally, C-3 carbonyl and 7V-methyl groups were developed by simple oxidation, reduction, and repeated oxidation steps. 

A partial synthesis of burnamicine (131) from geissoschizine methyl ether (130) takes advantage of the c/D ring cleavage of tetrahydro-/3-carbolines by means of ethyl chloroformate (Scheme 13),79 which simultaneously introduces a function into position 3, thereby facilitating the formation of the 3-oxo-substituent. An exactly analogous route was used for the synthesis of 19,20-dihydroburnamicine (133) from hirsutine (132). 

More recently, the same group (190) has described a partial synthesis of 16-epipleiocarpamine (367) from geissoschizine methyl ether (368) in a quite analogous series of reactions (Scheme 13). Treatment of geissoschizine methyl ether (368) with acetone/dry HC1 gave an aldehyde, and reaction with ethyl chlorocarbonate afforded the carbonate derivative 369... 

Scheme 13. Correlation of geissoschizine methyl ether (368) with 16-epipleiocarpamine (367).

Ueki T, Nishi A, Imamura S, Kanno H, Mizoguchi K, Sekiguchi K, et al. Effect of geissoschizine methyl ether, an indole alkaloid in Uncaria Hook, a constituent of Yokukansan, on human recombinant serotonin(7) receptor. Cell Mol Neurobiol 2013 33(l) 129-35. 

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