(5-chloro-1-benzofuran-2-yl)boronic acid

Conditions: temp:100.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 1.4 g (7.13 mmol) 5-chlorobenzofuranboronic acid, 1.24 g (5.30 mmol) 4-iodoanisole, 150 mg Pd(PPh3)4, 7.1 ml 1M aqueous sodium carbonate solution, and 25 ml 1,2-dimethoxyethane were heated in a sealed tube at 100° C. under argon overnight. It was cooled to room temperature and extracted with ethyl acetate. The organic layer was dried over sodium sulfate and concentrated under reduced pressure. 600 mg of the title benzofuran were obtained by crystallization from ethyl acetate and another 250 mg were obtained from the mother liquid after chromatography on silica gel with hexane. It was cooled to room temperature extracted with ethyl acetate The organic layer was dried over sodium sulfate concentrated under reduced pressure

Conditions: temp:-10.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 8.8 g (57.7 mmol) 5-chlorobenzofuran in 250 ml dry ether were added 7.32 g (63.0 mmol) tetramethylethylenediamine (TMEDA). The solution was kept below −60° C. under argon, while 37.5 ml of a 1.6M solution of butyllithium in hexane was added dropwise. It was warmed to −10° C. during 45 min and stirred at this temperature for another 30 min. The mixture was cooled again below −60° C. followed by dropwise addition of 35.7 g (190 mmol) triisopropyl borate. After warming to room temperature the mixture was quenched with 70 ml 2N hydrochloric acid and stirred for 1 h. The organic layer was washed three times with 30 ml 2N hydrochloric acid, twice with water, and extracted with 2N sodium hydroxide solution, successively. The alkaline aqueous layer was brought to pH5 and extracted with tert.-butylmethylether. All organic layers were combined, dried over sodium sulfate, and concentrated in vacuo to give the pale yellow crystalline boronic acid which was used for the next step without further purification. was added dropwise The mixture was cooled again below −60° C. After warming to room temperature the mixture was quenched with 70 ml 2N hydrochloric acid stirred for 1 h The organic layer was washed three times with 30 ml 2N hydrochloric acid twice with water, and extracted with 2N sodium hydroxide solution extracted with tert.-butylmethylether dried over sodium sulfate concentrated in vacuo

Conditions: temp:90.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 5-chlorobenzofuran-2-ylboronic acid (281 mg, 1.43 mmol) in dioxane (6 mL) was added ethyl 2-chloro-3-(isopropyl(methyl)amino)quinoxaline-6-carboxylate (140 mg, 0.48 mmol), K3PO4 (303 mg, 1.44 mmol), Pd(PPh3)4 (27.5 mg, 0.02 mmol) and water (3 drops) with stirring for 3 h at 90° C. in an oil bath maintained with an inert atmosphere of nitrogen. The reaction mixture was concentrated under vacuum to give a residue, which was applied onto a silica gel column with 1% ethyl acetate in petroleum ether to afford methyl 2-(5-chlorobenzofuran-2-yl)-3-(isopropyl(methyl)amino)quinoxaline-6-carboxylate as a light yellow solid (152 mg, 78%). maintained with an inert atmosphere of nitrogen The reaction mixture was concentrated under vacuum to give a residue, which

Conditions: temp:-10.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 5-chlorobenzofuran (14 g, crude) in dry tetrahydrofuran (250 mL) were added tetramethylethylenediamine (12.82 g, 110 mmol). The solution was kept below −60° C. under argon, while the solution of butyllithium in hexane (44 ml, 2.5 M) was added dropwise. It was warmed to −10° C. during 45 min and stirred at this temperature for another 30 min. The mixture was cooled again below −60° C. followed by dropwise addition of triisopropyl borate (51.88 g, 276 mmol). After warming to room temperature the mixture was quenched with hydrochloric acid (70 ml, 2N) and stirred for 1 h. The alkaline aqueous layer was brought to pH 5 and extracted with ethyl acetate (3×80 ml). All organic layers were combined, dried over sodium sulfate, and concentrated in vacuo to give 5-chlorobenzofuran-2-ylboronic acid (7.5 g) which was used for the next step without further purification. was added dropwise The mixture was cooled again below −60° C. After warming to room temperature the mixture was quenched with hydrochloric acid (70 ml, 2N) stirred for 1 h extracted with ethyl acetate (3×80 ml) dried over sodium sulfate concentrated in vacuo