DZ-Sinactine

Sinactine, C20H21O4N, is of interest in that the dZ-form had been obtained by Perkin (234) from cryptopine before it was discovered by Goto and Sudzuki (161) as the levorotatory form in Sinomenium aculum. It has since been isolated from Fumaria officinalis (77), where it occurs as a mixture of the I- and dU forms. It crystallizes from hot methanol in stout prisms which have [ ]d —312° (chloroform) and melt at 176°. Its hydrochloride (m.p. 272°) is sparingly soluble in water and serves as a convenient compound for isolation and purification. The alkaloid is readily oxidized by air, but the dehydro compound has not been recognized as a naturally occurring alkaloid. 

Structure and Synthesis. When Buck and Perkin (228) attempted to apply the Pictet and Gams synthesis (220) of berberine to epiberberine they obtained an isomer, tetrahydro- -epiberberine (XXXIII). Subsequently, Haworth and Perkin achieved a total synthesis which is detailed in connection with the synthesis of cryptopine. Oxidation of sinactine with iodine in boiling alcohol yields epiberberinium iodide, from which the chloride was prepared by treatment with silver chloride, and this was identical with epiberberinium chloride prepared from cryptopine (235). Finaly, Spath and Mosettig (236) resolved the dZ-tetrahydroepiberberine (m.p. 170°) (XLIII) from cryptopine by means of d- and Z-tartaric acids in succession and showed that the Z-form, [a] —302° (chloroform), was identical with the natural alkaloid. The cZ-form had the same numerical value for its optical rotation and melted at 178-179°. 

Constitution. The empirical formula of thalictrifoline and its ready oxidation indicates that it is a methyl homologue of either canadine or sinactine, that is, corydaline in which two of the methoxyls are replaced by a methylenedioxy group. On oxidation with iodine in methanol it is transformed into a quaternary iodide, which on reduction with zinc and hydrochloric acid yields dZ-thalictrifoline, m.p. 151°, which was also obtained by reduction of the naturally occurring dehydrothalictrifoline chloride. Complete oxidation of thalictrifoline yielded m-hemipinic acid, and therefore its structure was written as LXV. This was confirmed by demethylenation to a dihydroxy base and methylation of the latter. The new base proved to be an optically active stereoisomer of corydaline, presumably that of mesocorydaline, and on racemization by iodine oxidation and subsequent reduction was converted into mesocorydaline. 

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