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To a solution of 5-bromobenzofuran (3.9 g, 20 mmol) in dry THF (30 mL) cooled to -78C under N2-protected LDA (prepared from n-BuLi and /Pr2NH in THF (-30 mmol)) was slowly added. The mixture was stirred at the same temperature for 30 minutes, then triz'wpropylborate (5.64 g, 30 mmol) was added to the mixture. The mixture was allowed to warm to RT and stirred for 2 hours. The mixture was then quenched with IN HCl to pH=3 and extracted with EtOAc. The combined organic phases were combined, dried and filtered. The filtrate was concentrated to afford the desired product (4.3 g). MS (ESI) m/e (M+Ff1): 241.
4.3 g
To a solution of 5-bromobenzofuran (3.9 g, 20 mmol) in dry THF (30 mL) cooled to -78 C. under N2-protected LDA (prepared from n-BuLi and iPr2NH in THF (30 mmol)) was slowly added. The mixture was stirred at the same temperature for 30 minutes, then triisopropylborate (5.64 g, 30 mmol) was added to the mixture. The mixture was allowed to warm to RT and stirred for 2 hours. The mixture was then quenched with 1N HCl to pH=3 and extracted with EtOAc. The combined organic phases were combined, dried and filtered. The filtrate was concentrated to afford the desired product (4.3 g). MS (ESI) m/e (M+H+): 241.
With sodium carbonate;(1,1'-bis(diphenylphosphino)ferrocene)palladium(II) dichloride; In tetrahydrofuran; water; at 75℃;Reflux;
A suspension of the boronic acid from step 1 (1.44 mg, 6.0 mmol), 2-fluoro-4- iodobromobenzene (1.8 g, 6.0 mmol), Pd(dppf)Cl2 (600 mg), Na2CO3 (954 mg, 9.0 mmol) and in THF/H2O (9:1, 100 mL) was refluxed at 75C overnight under N2 protection. The mixture was cooled and filtered. The filtrate was washed with water (150 mL) and extracted with EtOAc (200 mL), washed with brine and dried over anhydrous sodium sulfate. The solution was evaporated and the residue was purified by column chromatography (PE / EA = 8:1-?5:1) to afford the desired compound. MS (ESI) m/e (M+H4): 370.
With (1,1'-bis(diphenylphosphino)ferrocene)palladium(II) dichloride; sodium carbonate; In tetrahydrofuran; water; at 75℃;Inert atmosphere;
A suspension of the boronic acid from step 1 (1.44 mg, 6.0 mmol), 2-fluoro-4-iodobromobenzene (1.8 g, 6.0 mmol), Pd(dppf)Cl2 (600 mg), Na2CO3 (954 mg, 9.0 mmol) and in THF/H2O (9:1, 100 mL) was refluxed at 75 C. overnight under N2 protection. The mixture was cooled and filtered. The filtrate was washed with water (150 mL) and extracted with EtOAc (200 mL), washed with brine and dried over anhydrous sodium sulfate. The solution was evaporated and the residue was purified by column chromatography (PE/EA=8:1?5:1) to afford the desired compound. MS (ESI) m/e (M+H+): 370.
methyl 3,5-diamino-6-(5-bromobenzofuran-2-yl)pyrazine-2-carboxylate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
49%
With tetrakis(triphenylphosphine) palladium(0); potassium carbonate; In methanol; toluene;Inert atmosphere; Reflux;
General procedure: <strong>[1458-01-1]Methyl 3,5-diamino-6-chloropyrazine-2-carboxylate</strong> 2 (1 eq.) was combined with K2CO3 (10 eq.), the appropriate (het)aryl boronic acid (1.5 eq.) and Pd(PPh3)4 (5 mol%) in a two-neck round bottom flask. The flask was connected to a condenser and purged with nitrogen. A 4:1 mixture of anhydrous toluene: MeOH (60 mL) was added via syringe and the reaction mixture was heated at reflux for 0.5-18 h. The mixture was allowed to cool to room temperature and filtered through Celite (10 x 3 cm, eluting with 3 x 20 mL EtOAc). The filtrate was evaporated to dryness and the residue purified by silica gel flash column chromatography using EtOAc/pet spirit.
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