1963 年 83 巻 2 号 p. 162-165
Treatment of berberine phenolbetaine (I) with acetic acid and zinc dust afforded colorless prisms of C20H21O4N (II), m. p. 169-171° and colorless feather shaped crystals of C20H21O4N (III), m. p. 180-181°. Both products showed ultraviolet spectra at λmaxEtOH 285mμ (log ε 3.71) but different infrared spectra (CHCl3). II was identified with trans-2, 3-methylenedioxy-9, 10-dimethoxy-5, 6, 13, 13a-tetrahydro-8H-dibenzo [a, g] quinolizine (m. p. 171-172°). On the basis of ultraviolet, infrared and nuclear magnetic resonance spectra, III was regarded to be a stereoisomer which possesses the same skeleton as that of II. III was presumed to have cis-quinolizidine structure, since it is already shown that II possesses trans-quinolizidine structure. As their infrared spectra in the region 2700-2800cm-1 did not provide a definite conclusion, their nuclear magnetic resonance spectra were determined in the two component solvent system. Since the proton exchange rate between nitrogen of the compound and trifluoroacetic acid in its solution of pyridine-trifluoroacetic acid system alters depending upon its shielding, the determination of the shift of proton signal of trifluoroacetic acid may indicate their conformational difference. Of their 3 mole% trifluoroacetic acid-pyridine solution proton signal in III shifted at higher field by 35.83 c. p. s. than that of II. It follows, therefore, from these results that III possesses a cis-quinolizidine structure.