图片来源：StrategicApplications of Named Reactions in Organic Synthesis
【Synthesis 1976, 767–768】
反应的底物应用范围极广，芳香羧酸，脂肪羧酸都适用此条件，手性氨基酸还原后还能保持很高的ee值。
反应机理
利用密度泛函理论计算，对这一机理进行了验证。
反应操作
Synthesis of Tf-DMAP, Tf-DPAP and Tf-MPLP
Into a solution of DMAP (61.1 g, 500.0 mmol.) in DCM (800.0 mL) was added(CF3SO2)2O (101.0 mL, 600.0 mmol, 1.2 equiv) at 0 oC. After addition, the mixture was warmed to room temperature and stirred for 4 h. The crude product was precipitated from the solution. After filtration, the solid was washed with DCM (400 mL × 4), then dried under reduced pressure to give the pure product as a white powder (191.9 g, 95%). The synthesis of Tf-DPAP and Tf-MPLP were similar to that of Tf-DMAP.
Synthesis of Tf-PPDP
Into a solution of 4-piperidin-1-ylpyridine (32.4 g, 200.0 mmol, 1.0 equiv.) in DCM (300.0 mL) was added (CF3SO2)2O (40.4 mL, 240.0 mmol, 1.2 equiv.) at 0 oC. After addition, the mixture was warmed to room temperature and stirred for 4h. Upon completion, 200 mL of n-hexane was added and the crude product precipitated out of solution. After filtration, the solid was washed with hexane (100 mL × 2), then dried under reduced pressure to give the pure product as a white powder (84.3 g, 95%).
General Procedure:
To a 25 mL Schlenk tube equipped with a magnetic stirring bar, carboxylic acid (0.3 or 1.0 mmol, 1.0 equiv), base (1.6 or 1.8 equiv) and DCM (2.0 ~ 5.0 mL) were added under a dry nitrogen atmosphere. Then the Tf-PPDP (1.7 equiv) and HBpin (1.1 ~ 1.8 equiv) were added to the reaction mixture. After the reaction was stirred for 10 min, the crude mixture was quenched by H2O and extracted by DCM (3 x 3.0 mL). The combined organic layers were dried over anhydrous Na2SO4. After the solvent was removed under reduced pressure, the resulting residue was purified by flash column chromatography on silica gel and eluted with petroleum ether/ethyl acetate to afford the desired aldehydes.
参考资料
