Organic compounds, potassium tert-butoxide

Potassium Potassium tert-butoxide Potassium hydride See under Alkali metals Organic compounds, sulfuric acid Air, chlorine, acetic acid, acrolein, acrylonitrile, maleic anhydride, nitroparaf-fins, /V-nitrosomethylurea, tetrahydrofuran, water... 

Under the protection of nitrogen, compound 3.58 (140 mg, 0.29 mmol) was dissolved in tetrahydrofuran (10 mL). Potassium tert-butoxide (0.29 mL, 0.29 mmol) was then added at 0 °C. The reaction was stirred at 0 °C for 30 min. Paraformaldehyde (87 mg, and 2.9 mmol) was quickly added, with continued stirring at 0 °C for 30 min. TLC showed that the reaction was completed. The reaction was quenched by saturated ammonium chloride solution (10 mL). The water phase was extracted with ethyl acetate (3 x 10 mL), and the organic phase was washed with saturated brine (2 x 10 mL). The combined organic phase was dried over anhydrous sodium sulfate. After filtration, the solvent was removed by reduced pressure. The resulting crude product was separated by flash column chromatography (PE/EA = 3 1) to give 99 mg colorless liquid (/ /= 0.85, PE/ EA = 1 1), yield 95 %. 

The reaction of 1,3-dinitrobenzenes with aryl iodides can be accomplished by using copper(I) tert-butoxide in situ prepared from CuCl and potassium rert-butoxide in dry DME. In this case, the reaction can be realized under essentially milder reaction conditions, at 70-110 C in the presence of pyridine as the base with respective yields. For instance, the biaryl 40 was produced from compounds 38 and 39 after 20 h at 67 C in DME / pyridine as the reaction solvent in 95% yield, respectively [38]. Dehalogenation products were isolated from many Ullmann reactions performed with the (relatively acidic) nitro-aryl halides, even when exclusion of water or acidic (protic) substances was provided. Furthermore, nitro-aryl halides are partially converted to triarylamines by reduction and subsequent exhaustive A -arylation [44,45]. Finnaly, it can be concluded that the Ullmann and related reactions are still valuable tools in the preparative organic chemistry providing a simple and usually efficient approach to simple symmetrical and certain classes of unsymmetrical biaryls. 

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