1955 年 75 巻 5 号 p. 533-536
2-Bromo-4-nordihydrosantonin, obtained by the bromination of 3-oxo-4-norisoeusanton-4-enic acid and 3-oxo-11-epi-4-noreusanton-4-enic acid, was submitted to dehydrobromination but 4-norsantonin was not obtained. Dehydrobromination of 2-bromo-11-carboxy-4-nordihydrosantonin (lactone: cis), obtained by the bromination of 11-carboxy-3-oxo-4-noreusanton-4-enic acid, also failed to yield 4-norsantonin. However, dehydrobromination of a crude brominated compound yielded 2-bromo-4-norsantonin which was assumed to be 2-bromo-6β-hodroxy-3-oxo-11-epi-4-norsantona-1, 4-dienic acid lactone.