通过Mitsunobo反应由醇制备氨基化合物

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氨基化合物也可以作为Mitsunobu 反应中的亲核试剂,取代羟基,生成取代的氨基化合物。同样,参与反应的胺必须有足够的酸性(pKa<13),能被PPh3/DEAD体系夺去质子。酰胺磺酰胺,亚胺和叠氮化合物都可以参与反应。


反应实例

1、利用苯磺酰胺合成胺


N-Boc p-toluenesulfonamide (88mg, 0.322 mmol) was dissolved in dry THF (3 mL) and PPh3 (168 mg, 0.645 mmol) was added. The solution was stirred under nitrogen and the alcohol (0.215 mmol) was added followed by DEAD (0.083 mL, 0.53 mmol). The mixture was stirred at room temperature for 3 h, concentrated in vacuo and the residue was purified by flash column chromatography (P: E 4: 1) to give the product (62%).(Henry, J. R; Marcin, L. R; Weinreb, S. M. Tetrahedron. Lett. 1989, 30, 5709.)

The de-protection was carried out according to the usual procedure.


2、利用DPPA 合成伯胺


To a cooled solution (-5oC) of DIAD (7.9 g, 93 mmol) in THF (5 mL) was added the substituted alchol (7.06 g, 18.7 mmol) and PPh3 (10.3 g, 39.1 mmol). After 15 min, diphenyl phosphorazidate (DPPA, 12.86 g, 46.77mmol) was added and the reaction mixture was allowed to warm to room temperature. After stirring overnight, the solvent was removed in vacuo to give a yellow oil. The crude material was purified by flash column chromatograghy (2:1,PE/Tol) to give the desired product (7.28 g, 91%) as a colorless oil. (Zuccarello, G; Bouzide, A; J. Org. Chem. 1998, 63, 4898.)

The de-protection and hydrogenation were routine operations.


3、分子内关环合成相应的环状胺


To a solution of substituted proline (33.6 g, 0.1 mol) and PPh3 (31.5 g, 0.12 mol) in THF (200 mL) was dropped a solution of DEAD (18.8 mL, 0.12 mmol) in dry THF (50 mL) at ice bath. The reaction mixture was allowed to warm to stirred 20oC for 2 h. The filtrate was evaporated and stirred with EA (100 mL), and the product was collected by filtration (20.66 g,74%). The solvent was removed under reduced pressure and the crude oil was purified by column chromatograghy to afford the desired product (27.3 g, 86%). (Bellettini, J. R; Miller, M. J. Tetrahedron.Lett 1997, 38, 167.)


4、合成丙二烯


An oven-dried, 500-mL, round-bottomed flask equipped with a large football-shaped Teflon-coated magnetic stirring bar is charged with 15.7 g (60.0 mmol) of triphenylphosphine under an argon atmosphere. The flask is sealed with a rubber septum containing a needle adapter to an argon-filled balloon, and 120 mL of THF is added via cannula. The solution is cooled in a −15°C bath, and 9.02 mL (57.5 mmol) of diethyl azodicarboxylate is added via syringe over 2 min, followed immediately by the addition of a solution of 8.52 g (50.0 mmol) of 3-(tert-butyldimethyl silyl)-2-propyn-1-ol in 18 mL of THF via cannula over 2 min. After an additional 5 min, a solution of 13.0 g (60.0 mmol) of o-nitrobenzenesulfonyl hydrazide in 65 mL of THF is added to the reaction mixture over 5 min via cannula. The resulting orange-red solution is stirred at −15°C for 45 min, after which time the cold mixture is allowed to warm to 23°C and is held at that temperature for 5 hr. During this time, the evolution of dinitrogen is observed. The reaction mixture is poured into a 2-L separatory funnel containing 400 mL of pentane, and the resulting mixture is washed with four 500-mL portions of ice-cold water. The organic layer is dried over anhydrous sodium sulfate, filtered, and concentrated by rotary evaporation at 0°C. The residue is purified by flash chromatography using a short column of 230-400 mesh silica gel (60 g, packed dry and eluted with pentane. The fractions containing the product are concentrated by rotary evaporation at 0°C to afford 5.38-5.39 g (70%) of (tert-butyldimethylsilyl)allene as a colorless liquid. (Organic Syntheses, Coll. Vol. 10, p.165; Vol. 76, p.178)

磺酰肼与α-羟基取代炔经过Mitsunobu氨基取代反应,生成的产物不稳定,马上分解为丙二烯化合物,这是一个制备丙二烯化合物的比较便捷的方法。


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