Reduction method and reduction product of alkenyl active methylene compound

Abstract

Disclosed are a reduction method and reduction product of an alkenyl active methylene compound. The reduction reaction comprises the following steps: taking an alkenyl active methylene compound as a substrate, a metal hydride as a reducing agent, and a palladium compound as a catalyst, performing a reduction reaction to obtain a reduction product, and then reducing the alkenyl active methylene compound. The reduction system is a simple method for reducing the alkenyl active methylene compound, and the used hydride and palladium compound catalyst are both reagents that could easily be obtained in a laboratory. Compared with conventional hydrogen hydrogenation methods and reduction methods of reducing agents, the method is easier to operate, higher in safety, mild in conditions, and high in reaction yield, a reaction in a one-pot two-step manner can be achieved, and high atom economy and step economy can be obtained.

Claims

1. A method of reducing an alkenyl active methylene compound comprising: reacting the alkenyl active methylene compound with a metal hydride in the presence of a palladium compound in an organic solvent, wherein the alkenyl active methylene compound has the following structure: ##STR00007## R.sup.1 and R.sup.2 are independently selected from the group consisting of hydrogen, alkyl, phenyl, substituted phenyl, naphthyl, pyridyl, and quinolinyl, EWG is selected from the group consisting of —COC.sub.6H.sub.5, —COOCH.sub.2CH.sub.3, —COCH.sub.3, and —CON(CH.sub.3).sub.2, and EWG′ is selected from the group consisting of hydrogen, —COC.sub.6H.sub.5, —COOCH.sub.2CH.sub.3, —COCH.sub.3, and —CON(CH.sub.3).sub.2; wherein the metal hydride is sodium hydride, lithium hydride, potassium hydride, or calcium hydride; wherein the palladium compound is palladium chloride, palladium acetate, Pd(MeCN).sub.2Cl.sub.2, [(η.sup.3-C.sub.3H.sub.5)PdCl].sub.2, Pd(TFA).sub.2, Pd(dppp)Cl.sub.2, Pd.sub.2(dba).sub.3, Pd(C.sub.6H.sub.5CN).sub.2Cl.sub.2, Pd(OH).sub.2, Pd/C, Pd(PPh.sub.3).sub.4, or Pd(PPh.sub.3).sub.2Cl.sub.2; and wherein the organic solvent is DMA (dimethylacetamide), DMF (dimethylformamide), THF (tetrahydrofuran), DME (dimethoxyethane), or dioxane.

2. The method according to claim 1, wherein a molar ratio of the palladium compound:the metal hydride:the alkenyl active methylene compound is 0.05:(1.5 to 2.5):1.

3. The method according to claim 2, wherein a molar ratio of the palladium compound:the metal hydride:the alkenyl active methylene compound is 0.05:2:1.

4. The method according to claim 1, wherein the reduction of the alkenyl active methylene compound is performed under the protection of nitrogen atmosphere, at 0° C. to 50° C., for 0.5 to 5 hours.

5. The method according to claim 4, wherein the reduction of the alkenyl active methylene compound is at room temperature, for 45 minutes.

Description

EMBODIMENTS OF THE INVENTION

Example 1

(1) ##STR00002##

(2) Under the protection of nitrogen, palladium chloride (1.7 mg, 0.01 mmol, 5 mol %) and sodium hydride (60% in oil, 16 mg, 0.4 mmol, 2 equiv.) were stirred and suspended in DMA (1.0 mL) for 5 min at room temperature, and then the compound 1h (0.2 mmol) in DMA (0.5 mL) was added. The reaction was performed at room temperature for 45 min. The reaction was quenched by adding a saturated aqueous ammonium chloride solution. The product was subjected to extraction with ethyl acetate, combining the extract, drying with sodium sulphate, rotary evaporation, and column chromatography to obtain the product 2 h with a yield of 99%. .sup.1H NMR (400 MHz, CDCl.sub.3): δ 8.00 (d, J=7.7 Hz, 2H), 7.60 (t, J=7.3 Hz, 1H), 7.48 (t, J=7.6 Hz, 2H), 7.34-7.26 (m, 4H), 7.25-7.19 (m, 1H), 4.66 (t, J=7.3 Hz, 1H), 4.18-4.08 (m, 2H), 3.43-3.30 (m, 2H), 1.15 (t, J=7.1 Hz, 3H). .sup.13C NMR (151 MHz, CDCl.sub.3): δ 194.61, 169.40, 138.57, 136.33, 133.64, 129.06, 128.81, 128.78, 128.65, 126.76, 61.63, 56.32, 34.89, 14.07. LR-MS (ESI): m/z 283.2 [M+H]+.

(3) ##STR00003##

(4) Under the protection of nitrogen, palladium chloride (1.7 mg, 0.01 mmol, 5 mol %) and sodium hydride (60% in oil, 16 mg, 0.4 mmol, 2 equiv.) were stirred and suspended in DMA (1.0 mL) for 5 min at room temperature, then the compound 1h (0.2 mmol) in DMA (0.5 mL) was added. The reaction was performed at room temperature for 45 min, and benzyl bromide (1.5 eq.) was added. After the reaction was complete, the reaction was quenched by adding a saturated aqueous ammonium chloride solution. The reaction mixture was extract with ethyl acetate. The organic phase was collected and dried by rotary evaporation. Column chromatography gave the compound 3 h with a yield of 98%.

Example 2

(5) ##STR00004##

(6) Under the protection of nitrogen, palladium chloride (34 mg, 0.01 mmol, 5 mol %) and sodium hydride (60% in oil, 16 mg, 0.4 mmol, 2 equiv.) were stirred and suspended in DMA (1.0 mL) for 0.75 h at room temperature, and then the compound 1i (0.2 mmol) in DMA (0.5 mL) was added. The reaction was quenched by adding a saturated aqueous ammonium chloride solution. The reaction mixture was extract with ethyl acetate. The organic phase was collected and dried by rotary evaporation. Column chromatography gave the compound 2i with a yield of 98%. .sup.1H NMR (400 MHz, CDCl.sub.3): δ 7.31-7.14 (m, 5H), 4.14 (q, J=7.0 Hz, 2H), 3.78 (t, J=7.6 Hz, 1H), 3.16 (d, J=7.5 Hz, 2H), 2.19 (s, 3H), 1.20 (t, J=7.1 Hz, 3H). .sup.13C NMR (151 MHz, CDCl.sub.3): δ 202.63, 169.22, 138.23, 128.89, 128.67, 126.78, 61.60, 61.42, 34.08, 29.77, 14.14. LR-MS (ESI): m/z 221.1 [M+H]+.

Example 3

(7) ##STR00005##

(8) Under the protection of nitrogen, stirring suspended palladium chloride (1.7 mg, 0.01 mmol, 5 mol %) and sodium hydride(60% in oil, 16 mg, 0.4 mmol, 2 equiv), are in DMA (1.0 mL) for 5 min at room temperature, then add the compound 1j (0.2 mmol) in the solution of DMA (0.5 mL), the reaction is performed at room temperature for 45 min, the reaction is stopped by adding the solution of saturated aqueous ammonium chloride, the product is subjected extraction with ethyl acetate, combine extract, drying with sodium sulphate, rotary evaporation, and column chromatography to obtain the product 2j with a yield of 97%.

(9) Under the protection of nitrogen, palladium chloride (1.7 mg, 0.01 mmol, 5 mol %) and sodium hydride (60% in oil, 16 mg, 0.4 mmol, 2 equiv.) were stirred and suspended in DMA (1.0 mL) for 5 min at room temperature, and then the compound 1j (0.2 mmol) in DMA (0.5 mL) was added. The reaction was quenched by adding a saturated aqueous ammonium chloride solution. The reaction mixture was extract with ethyl acetate. The organic phase was collected and dried by rotary evaporation. Column chromatography gave the compound 2j with a yield of 97%. .sup.1H NMR (400 MHz, CDCl.sub.3): δ 8.04 (d, J=8.2 Hz, 1H), 7.86 (d, J=7.8 Hz, 1H), 7.78-7.70 (m, 1H), 7.58-7.46 (m, 2H), 7.37 (d, J=4.4 Hz, 2H), 4.24-4.07 (m, 4H), 3.84 (t, J=7.4 Hz, 1H), 3.71 (d, J=7.4 Hz, 2H), 1.19 (t, J=7.0 Hz, 6H). .sup.13C NMR (101 MHz, CDCl.sub.3): δ 169.17, 134.03, 133.95, 131.71, 129.10, 127.79, 127.30, 126.40, 125.77, 125.53, 123.35, 61.65, 53.01, 31.94, 14.14. LR-MS (ESI): m/z 301.1 [M+H]+.

Example 4

(10) ##STR00006##

(11) Under the protection of nitrogen, stirring suspended palladium chloride (17 mg, 0.01 mmol, 5 mol %) and sodium hydride (60% in oil, 16 mg, 0.4 mmol, 2 equiv), are in DMA (1.0 mL) for 5 min at room temperature, then add the compound 1k (0.2 mmol) in the solution of DMA (0.5 mL), the reaction is performed at room temperature for 0.75 h, the reaction is stopped by adding the solution of saturated aqueous ammonium chloride, the product is subjected extraction with ethyl acetate, combine extract, drying with sodium sulphate, rotary evaporation, and column chromatography to obtain the product 2k with a yield of 97%.

(12) Under the protection of nitrogen, palladium chloride (1.7 mg, 0.01 mmol, 5 mol %) and sodium hydride (60% in oil, 16 mg, 0.4 mmol, 2 equiv.) were stirred and suspended in DMA (1.0 mL) for 5 min at room temperature, and then the compound 1k (0.2 mmol) in DMA (0.5 mL) was added. The reaction was quenched by adding a saturated aqueous ammonium chloride solution. The reaction mixture was extract with ethyl acetate. The organic phase was collected and dried by rotary evaporation. Column chromatography gave the compound 2k with a yield of 97%. .sup.1H NMR (400 MHz, CDCl.sub.3): δ 7.89 (d, J=7.1 Hz, 2H), 7.55 (t, J=6.6 Hz, 2H), 7.44 (d, J=7.2 Hz, 2H), 7.31-7.17 (m, 5H), 4.70-4.55 (m, 1H), 3.43-3.26 (m, 2H), 2.90 (s, 3H), 2.77 (s, 3H). .sup.13C NMR (101 MHz, CDCl.sub.3): δ 195.34, 169.30, 139.32, 136.22, 133.41, 129.20, 128.90, 128.64, 128.35, 126.75, 54.73, 37.40, 36.01, 35.54. LR-MS (ESI): m/z 282.2 [M+H]+.