Studies on Tropolones () -Methyltropolone Synthesis and Its -Isomer

[摘要] By the three-step synthesis of alkyltropolone from five-membered cyclopentadiene, as described in Part ¥°, methyltropolone has been prepared. From the hydrolysis product of dichloroketene-methylcyclopentadiene cycloadduct, ¥â-(¥°) and ¥ã-methyltropolone (¥±) were separated, with the first predominating, by means of repeated fractional recrystallization and fractional vacuum sublimation. The total yield of these methyltropolones in the hydrolysis step was about 40%. Comparison of this result with those obtained in part ¥° revealed the following order as the relative readiness of their preparation: tropolone > methyltropolone > ethyltropolone. The reason for formation of the isomeric (¥±) was discussed by an interpretation of NMR spectrum of cycloadduct in the unsaturation and methylgroup region.

[学科分类] 化学（综合）