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Eaton试剂（伊顿试剂），7.7 wt% 的五氧化二磷的甲磺酸溶液，此试剂可以代替多聚磷酸用于催化酰基化反应。最常用是关环反应（五元或六元环）。
Dihydrojasmone (2). To a solution of Eaton reagent (formed by addition of 36 g P2O5 to 360 g freshly distilled methanesulfonic acid and stirred for 1–2 h till all dissolved) was added g-methylg-decanolactone 1 (4.91 g) in small portions. After 33 h at 25 C the yellow solution was added dropwise to 1 L water and let stand for 10 min. Extraction with CHCl3, workup and distillation at 90–91 C/2 Torr afforded 4.08 g (92%) of 2.
【Eaton P E,J Org Chem.,1973, 38, 4071】
Enamine diester 1a (1.8g, 6.6 mmol), was added to a RBF that was equipped with a thermocouple and a stirrer. Eaton’s reagent (7 mL) was then added to the flask. Reaction mixture was aged at 50 o C, and progress of reaction was followed by HPLC. HPLC conditions: Zorbax RX-C8 column, 150 x 3 mm, gradient method, ACN:0.1% H3PO4 15:85 over 20 min hold 5 min at 80:20 then to 15:85 over 1 min. Flow rate = 1 mL/min, λ = 210 nm. Retention time, 1a = 18.0 min, 1b = 12.2 min. When conversion was ≥ 98 %, reaction mixture was cooled to 5 o C and slowly transferred to an excess saturated sodium carbonate solution (10 eq.) that was cooled to 10 o C. Solid was filtered and washed with water (20 mL) and was dried in a vac. oven at 50 o C for 12 h. 1b was isolated in 97% yield (1.5g, 6.4 mmol) .
【Zewge D,J Org Chem.,2007, 72, 4276】
1 Eaton P EJ Org Chem1973 38 4071
2 Ren R XTet Lett2001 42 8441
3 Lee KIBull Kor Chem Soc2007 28 1203
4 Zewge DJ Org Chem2007 72 4276