1992年Kennedy, R. M. 等人報道了5-羥基烯烴和氧化錸(VII) (Re2O7)反應(yīng)得到2-羥甲基四氫呋喃的反應(yīng)。此氧化環(huán)化反應(yīng)是順式加成，產(chǎn)量穩(wěn)定，但有少量的醇被氧化為羰基化合物。
盡管此反應(yīng)有很高的立體選擇性，但為了讓底物完全反應(yīng)需要加入多余化學(xué)當(dāng)量的Re2O7。后來改進(jìn)法加入了另一種氧化劑H5IO6共同反應(yīng)，只需要催化量的Re2O7就可以將5-羥基烯烴氧化為相應(yīng)的四氫呋喃羥甲基化合物，
Mechanism
General procedure
化學(xué)當(dāng)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進(jìn)行反應(yīng)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.
參考文獻(xiàn)
1. Kennedy, R. M.; Tang, S. TetrahedronLett. 1992, 33, 3729.
2. Tang, S.; Kennedy, R. M. TetrahedronLett. 1992, 33, 5303.
