Hauser-Kraus环化反应 / 开普饭

碱性条件下，苯酞类化合物和α，β-不饱和羰基化合物立体选择性关环得到苯并氢醌的反应。加入氧化银氧化氢醌可以制备苯醌。

反应机理

反应实例

Hydroquinone (4). To LDA (3.3 mmol) in THF (4 mL) and HMPA at -78 ℃ was added 3-cyanophthalide 1 (3 mmol) in THF (3 mL) over 2 min. After 10 min stirring at -78 ℃, 2 (3 mmol) in THF (3 mL) was added over 1 min. After warming to 0 ℃, the mixture was quenched with AcOH and diluted with Et2O and water. Workup and chromatography yielded pure hydroquinone 4.

【 Tet Lett., 1978, 19, 2263】

Quinone (11). To a stirred solution of tBuOLi (9.84 mmol) in THF (40 mL) at -60 ℃ was added a solution of phthalide 9 (3.28 mmol) in THF (5 mL) under N2. After stirring the yellowish solution at -60 ℃ for 25 min, 10 (1.5 eq) in THF (5 mL) was added and stirring continued for 1 h at the same temp and further 2–6 h at r.t. Usual workup and chromatography or recrystallization afforded 11 in 66%

yield.

【J Org Chem., 2007, 72, 4981】