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With potassium acetate;dichloro[1,1'-bis(di-t-butylphosphino)ferrocene]palladium(II); In water; acetonitrile; for 50h;Inert atmosphere of nitrogen; Heating; Reflux; |
To a mixture of 4,4,4',4',5,5,5',5'-octamethyl-2,2'-bi(l,3,2-dioxaborolane) (3.09 g), 5- bromobenzo[d]oxazol-2(3H)-one (2 g) and potassium acetate (2.75 g) in acetonitrile (20 mL) and water (15 mL), under a nitrogen atmosphere was added 1,1 bis{-tert- butylphosphino)ferrocene palladium dichloride (61 mg) and the mixture stirred and heated under reflux for 5O h. The cooled reaction mixture was concentrated under vacuum and the residue partitioned between water (100 mL) and diethyl ether (200 mL). The layers were separated and the organic extract was dried over magnesium sulfate and concentrated to dryness to afford a viscus oil. The crude product was purified by chromatography on silica eluting with ethyl acetate / ohexane (20:80) to afford the sub-titled compound (1.1 g).1H NMR (399.824 MHz, CDCl3) delta 9.03 (s, IH), 7.61 (dd, IH), 7.53 (s, IH), 7.21 (d, IH), 1.35 (s, 12H). |
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With dichloro(1,1'-bis(diphenylphosphanyl)ferrocene)palladium(II)*CH2Cl2; potassium acetate; In tetrahydrofuran; at 80℃; for 72h;Inert atmosphere; |
10. Preparation of 5-(4,4,5,5-tetramethyl-1 ,3,2-dioxaborolan-2-yl)benzo[d]oxazol-2(3H)- one 5-Bromo-2-benzoxazolinone (200 mg, 0.935 mmol),bis(pinacole)diborane (309 mg, 1.215 mmol), potassium acetate (275mg, 2.80 mmol) and Pd(dppf)C12.CH2CI2 (153 mg, 0.187 mmol) were loaded in a microwave vial. The capped vial was evacuated using high vacuum and purged with nitrogen (each three times). Dry THE (4 mL) was added and the mixture was degassed again by using the high vacuum and purged with nitrogen again (each threetimes). The mixture was heated conventional at 80 C for 3 days before it was filtered over Celite and the residue was washed with CHCI3IMeOH. The filtrate was concentrated in vacuum and the resulting brown oil was purified by chromatography on silica gel (biotage, DCM/EtOH) to give the product (40 mg, 16%, purity 76%) as a light yellow sticky solid containing bis(pinacole)diborane. 1H-NMR (500 MHz, CDCI3) ppm = 7.99 (bs,1H).7.62 (dd, J=8.0, 1.0, IH), 7.50 (s, IH), 7.22 (d, J=8.0, 1H), 1.36 (s, 12H). HRMS m/z(ESl) [M+H] C13H16BN04, calc 261.1281, found 261.1284, Rt = 2.89 mm (HPLC methodE). |