主要用于芳基酮或二芳基酮的還原。
反應(yīng)實例
1 Et3SiH-BF3還原示例1
A dry, 250-mL, three-necked, round-bottomed flask is equipped with a magnetic stirring bar, a gas-inlet tube, a pressure-equalizing dropping funnel, and a Dewar condenser cooled with ice-water and fitted with a drying tube containing anhydrous calcium sulfate (Drierite). A solution of 20.9 g (0.180 mol) of triethylsilane in 80 mL of dichloromethane is placed in the flask. The solution is stirred rapidly and cooled in an ice bath while boron trifluoride gas is introduced below the surface of the liquid at a moderate rate. The first appearance of white fumes at the exit of the drying tube indicates that the solution is saturated and the apparatus is filled with boron trifluoride. The flow of boron trifluoride is adjusted to a level sufficient to maintain a slight emission of white fumes from the drying tube, and a solution of 10.0 g (0.0606 mol) of m-nitroacetophenone in 30 mL of dichloromethane is added dropwise during 10 min. Stirring and cooling are continued for 30 min, after which the flow of boron trifluoride gas is stopped and the cooling bath is removed. The mixture is stirred at room temperature for 20 min, cooled again with the ice bath, and hydrolyzed by adding 20 mL of aqueous saturated sodium chloride. The upper organic layer is decanted from the salts, which are then dissolved in 50 mL of water. The aqueous solution is extracted with two 25mL portions of pentane, which are combined with the original organic layer. The organic solution is washed with two 25 mL portions of saturated sodium chloride and dried with anhydrous sodium sulfate. Distillation at atmospheric pressure through a 10-cm Vigreux column serves to separate solvent and ca. 15 g of a mixture of primarily triethylsilane and triethylfluorosilane, bp 106–109°C. The remaining liquid is distilled in a short-path distillation apparatus under reduced pressure, affording 8.33–8.38 g (91–92%) of pale yellow m-nitroethylbenzene, bp 120–121°C (15 mm), 134–135°C (22 mm), nD25 1.5330.
2 Et3SiH-TFA 還原示例2
To a solution of 1 (2 g, 6.97 mmol) in CF3COOH (7 mL) and MeNO2 (5 mL) (to aid solution) was added Et3SiH (2 g) over 5 min. The mixture was stirred at room temperature for 96 h, after which time a yellowish precipitate had formed on the sides of the flask. Acetone (20mL) was added to dissolve the precipitate, followed by 30 mL of H2O, and the solution clarified. The filtrate was basified at 15 oC to pH 8 with concentrated NH4OH, and the resultant precipitate filtered, washed with water, and dried, followed by re-crystallization from anhydrous Et2O. This produced 1.86 g (98%) of 2 as a yellow powder: mp 82-84 oC; MS (M+) 273; 1H NMR (80 MHz, CDC1,) δ 3.96 (s, 2, CH2), 7.24 (m, 5, C6H5), 8.37 (br s, 4,NH2 and 2,6-H2).
參考文獻(xiàn)
1. Organic Syntheses, Coll. Vol. 7, p.393; Vol. 60, p.108
2. Kwasi A. Ohemengt and Barbara Roth J. Med. Chem. 1991,34, 1394-1399
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