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Kennedy氧化环化反应

浏览:9 日期:09-25 10:17


1992年Kennedy, R. M. 等人报道了5-羟基烯烃和氧化铼(VII) (Re2O7)反应得到2-羟甲基四氢呋喃的反应。此氧化环化反应是顺式加成,产量稳定,但有少量的醇被氧化为羰基化合物。

尽管此反应有很高的立体选择性,但为了让底物完全反应需要加入多余化学当量的Re2O7。后来改进法加入了另一种氧化剂H5IO6共同反应,只需要催化量的Re2O7就可以将5-羟基烯烃氧化为相应的四氢呋喃羟甲基化合物,


Mechanism


 

General procedure

化学当量 rhenium (VII) oxide1.

To a solution of 1 mmol of 5-hydroxyalkenes and 1.1mmol of 2, 6-lutidine in 5 ml of methylene chloride at room temperature wasadded 1.1 mmol of Re2O7. The rhenium (VII) oxidedissolved rapidly providing a red solution that gradually yielded a blackprecipitate as the reaction proceeded. After 1 hr, 1.1 mmol of 2, 6-litidinefollowed by 1.1 mmol of rhenium (VII) oxide were added. This sequence wasrepeated again after another hour. After 8 hrs, 10 mmol of sodium hydroperoxidewas added as a 1 M aqueous solution. The resulting colorless mixture wasstirred for 30 minutes, and then diluted with 10 ml of methylene chloride. Theorganic layer was washed with 10 ml of 1 N HCl to remove 2, 6-lutidine followedby 10 ml of saturated NaCl solution. The products were then purified byflashchromatography on silica gel.

催化量rhenium (VII) oxide (Re2O7) 和 H5IO6进行反应2.

To a mixture of 1.0 mmol of 5-hydroxyalkene and 1.3mmol of periodic acid (H5IO6) in CH2Cl2at room temperature, was added 0.5 mmol rhenium (VII) oxide (Re2O7).The reaction was    monitored by TLC untilall starting material was consumed (about 15 hr). Then, 10 equivalents of NaHSO3as 1.0 M aqueous solution was added. After stirring for 30 min, the reactionmixture was diluted with CH2Cl2 and the product waspurified in normal fashion.

参考文献

1.       Kennedy, R. M.; Tang, S. TetrahedronLett199233, 3729.

2.       Tang, S.; Kennedy, R. M. TetrahedronLett199233, 5303.




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