Base II is a tertiary base obtained from
Corydalis ambigua CHAM et SCHLECHT. var.
amurensis MAXIM., with m.p. 144-146°, [α]
D12±306.0° (CHCl
3); (±) form of m.p. 190-191°, and dehydro base (iodide) of m.p. 282° (decomp.). It was assumed to be a protober-berine-type base from its ultraviolet spectrum (Fig. 1). Its nuclear magnetic resonance spectrum (Fig. 2) and analytical values indicated the presence of two methoxyls, one methylenedioxy group, and one methyl bonded to a secondary carbon. Cleavage of methylenedioxy group with phloroglucinol-sulfuric acid followed by methylation with diazomethane gave corydaline (I) (Chart 1), from which it was proved that the methoxyl and methylenedioxy group are situated at 2, 3, 9, and 10-positions, and the methyl group at 13-position. Consequently, base II must be either thalictricavine (VII) or thalictrifoline (VIII), but various properties of base II are not in agreement with those of VII or VIII, as shown in Teble II, and their infrared spectra are different (cf. Fig. 4).
It was possible that base II is a stereoisomer of VII or VIII, and these compounds were compared in the form of an anhydro base which does not contain any asymmetric carbon atoms. As a result, dehydro-base II agreed with dehydrothalictriflinium iodide (XI) in melting point, Rf, and infrared spectrum (Fig. 5), but not with dehydrothalictricavinium iodide (X). Consequently, it was found that base II has the same planar structure as VIII with different steric configuration. The infrared spectrum (Fig. 6) of base II exhibits abosorption of
trans-quinolinidine at 2700cm
-1, which is not present in the spectrum of VIII. Dehydration with mercuric acetate showed that base II has a
trans-quinolizidine skeleton, while VIII has the
cis-quinolizidine skeleton. The dehydro-base II, obtained as the quaternary base, was found to be none other than dehydrothalictrifoline.
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