Coreximine, structure

Structure. Coreximine has two methoxyls and two phenolic hydroyls, and when methylated with diazomethane it yields a tetramethoxy compound, melting at 177°. Ethylation similarly yields a dimethoxydiethoxy base melting at 131° (28). The tetramethoxy compound is isomeric but not identical with tetrahydropalmatine, and like the latter it is readily oxidized in air to a yellow base, and when racemized by oxidation with mercuric acetate followed by reduction with zinc and hydrochloric acid it gave rise to a base (m.p. 157°) identical with norcoralydine (LXIX) (227). Coreximine is therefore a bisdesmethyl derivative of LXIX (271). Four such compounds are possible if vicinal hydroxy compounds are excluded. 

Four new alkaloids of the quaternary berberine type, but with the coreximine orientation of oxygen substituents, have been found in Isopyrum thalictroides. The structures of these pseudoberberines were determined as (61 R = = Me),... 

Structures assigned to certain tetrahydroberberine alkaloids have been shown to be incorrect, the bases being identified with known compounds by comparison with authentic specimens. The bases concerned are aequaline, coramine, schefferine, kikemanine, and discretinine, which have been shown to be identical with discretamine (56 R =R = H), coreximine (57), (-)-corydalmine (56 R Me, R = H), (-)-corydalmine, and corypalmine (56 R =H, R = Me) respectively. The structure of discretamine has been confirmed by synthesis of the racemate from the tetrahydroisoquinoline (58 R = PhCH2, R = Me) by its... 

This generalization has recently been used to correct the structures of a variety of tetrahydroprotoberberine alkaloids. Aequaline was shown to be identical with discretamine, and coramine with coreximine. Schefferine is the same as kikemanine, and discretinine corresponds to corypalmine. ... 

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