59% |
With bis-triphenylphosphine-palladium(II) chloride; potassium hydrogencarbonate; In 1,4-dioxane; water; at 100℃; for 3h;Inert atmosphere; |
General procedure: To a degassed solution of ethyl 2-(2-((7-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2- yl)benzofuran-5-yl)methoxy)phenyl)acetate (le) (2 g, 4.58 mmol) in dioxane (24 mL) was added 4-bromothiophene-2-carbaldehyde (0.876 g, 5.01 mmol), bis(triphenylphosphine)Palladium(II)chloride [Pd(PPh3)2Cl2] (0.527 g, 0.751 mmol), a solution of K2CO3 (2.076 g, 15.02 mmol) in water (8 mL) and heated at 90 C for 3 h on oil bath under a nitrogen atmosphere. The reaction mixture was cooled to room temperature diluted with EtOAc (100 mL) and water (15 mL). The organic layer was separated, and aqueous layer was extracted with ethyl acetate (100 mL). The combined organic layers were dried, filtered and evaporated to dryness. The residue obtained was purified by flash column chromatography [silica gel 12 g, eluting with DMA-80 in DCM from 0-50%] to give ethyl 2- (2-((7-(5-formylthiophen-3-yl)benzofuran-5-yl)methoxy)phenyl)acetate (If) (2.022 g, 100 % yield) as a yellow syrup. NMR (300 MHz, DMSO-7e) 5 10.11 - 10.02 (m, 1H), 8.70 (s, 2H), 7.83 (d, 7 = 1.6 Hz, 1H), 7.72 (d, 7 = 1.6 Hz, 1H), 7.30 - 7.25 (m, 1H), 7.25 - 7.21 (m, 2H), 7.14 - 7.09 (m, 1H), 7.08 (d, 7 = 2.2 Hz, 1H), 6.92 (td, 7 = 7.4, 1.1 Hz, 1H), 5.24 (s, (0171) 2H), 3.98 - 3.92 (m, 2H), 3.65 (s, 2H), 1.00 (t, 7= 7.1 Hz, 3H). |