Abstract: Commercially available and inexpensive potassium bis(trimethylsilyl)amide (KHMDS) serves as an efficient transition metal-free catalyst for the catalytic sp C?H silylation of several terminal alkynes including two pharmaceuticals. Overall, the presented system allows the synthesis of various attractive silylacetylenes under mild conditions, making this approach an environmentally benign and sustainable alternative to existing synthetic solutions.
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(5Z)-5-[(pyridin-2-yl)methylene]-5H-furan-2-one[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
72%
With copper(l) iodide; palladium 10% on activated carbon; triethylamine; triphenylphosphine; In 1,4-dioxane; at 25 - 80℃; for 3.5h;Inert atmosphere;
General procedure: (a) The reaction was performed in a bigger scale using 100 mg of 10% Pd/C (0.092 mmol), PPh3 (0.37 mmol), CuI (0.184 mmol), Et3N (10.68 mmol), compound 1a (3.56 mmol), and acetylenic compound 2a (5.32 mmol) in 1,4-dioxane (20.0 mL). After stirring at 80 C for 3 h under nitrogen the mixture was cooled to room temperature. The Pd/C was filtered off and washed with water (2 10 mL), acetone (2 10 mL), and EtOAc (2 10 mL). Then the catalyst was collected, dried at 100 C in an oven, and reused for the next run. The co-catalyst CuI along with PPh3 was added in every repeated run. (b) General method for the preparation of 3: A mixture of compound 1 (0.89 mmol), 10% Pd/C (0.023 mmol), PPh3 (0.092 mmol), CuI (0.046 mmol), and Et3N (2.67 mmol) in 1,4-dioxane (5.0 mL) was stirred at 25 C for 30 min under nitrogen. The acetylenic compound 2 (1.33 mmol) was added slowly with stirring. The mixture was then stirred at 80 C for 3 h, cooled to room temperature, diluted with EtOAc (30 mL), and filtered through celite. The filtrate was collected and concentrated. The residue was purified by column chromatography (2-15% EtOAc/hexane) to afford the desired product
With bis-triphenylphosphine-palladium(II) chloride; copper(l) iodide; triethylamine; In 1,4-dioxane; at 100℃; for 4h;Inert atmosphere;
To a solution of 10 (500mg, 1.Smmoi) in 5mL of dry dioxane was added 11(300mg, 2.9mmoi), CuT (30mg. 0.iSmmoi), Pd( Ph3)2C12 (70mg, 0.iSrnmoi) and TEA (400mg, 3.9mmoi). The mixture was degassed under vacuo and purged with N2 for several times. Then the mixture was stirred at 100C for 4h. TLC showed the obtaining of the product. The mixture was concentrated. The crude was washed with water (2OrnL) and extracted with EtOAc (8OmL).The organic layer was washed with water and brine, dried over anhydrous Na2SO4 and concentrated. The residue was purified by prepTLC to give product 12 (450 mg, yield: 94.3%).LCMS: m/z, 3 19.1 (M+H).
With 1,4-diaza-bicyclo[2.2.2]octane; copper(II) tungstate; In water; at 60℃;Green chemistry;
General procedure: To a mixture of isatin (1 equiv.) and phenyl acetylene (1.2 equiv.) in water (3 mL), CuWO4 (10 mol%) and DABCO (40 mol%) were added at room temperature and the mixture was heated at 60 C for 2 to 5 h. After completion of reaction (monitoring by TLC) mixture was cooled to room temperature and extracted with EtOAc (2×10 mL). The organic layers were washed with brine, dried using sodium sulfate. Evaporation of the solvent gave the crude product which was purified by silica gel column chromatography to give 3-hydroxy-3-(phenylethynyl)indolin-2-ones (3a-3u).
Chemistry
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