81% |
With dichloro(1,1'-bis(diphenylphosphanyl)ferrocene)palladium(II)*CH2Cl2; potassium acetate; In 1,4-dioxane; at 100℃; for 3h;Inert atmosphere; |
To a stirred solution of dimethyl 2-bromobenzene-1 ,4-dicarboxylate (15.8 g, 57.9 mmol) in 1 ,4 dioxane (140 mL) was added fused potassium acetate (17.2 g, 174 mmol), 4,4,5,5-tetramethyl-2- (4,4,5,5-tetramethyl-1 ,3,2-dioxaborolan-2-yl)-1 ,3,2-dioxaborolane (19.1 g, 75.2 mmol) and finally [1 , 1 - Bis(diphenylphosphino) ferrocene]-dichloropalladium(ll) dichloromethane adduct (2.41 g, 2.89 mmol) under nitrogen. The reaction mixture was heated at 100C for 3 h. The reaction mixture was cooled to ambient temperature and diluted with water (100 mL) and then extracted with ethyl acetate (3 x 200 mL). Combined organic layer was washed with water (3 x 200 mL) followed by brine wash (200 mL). Organic layer was dried over sodium sulfate, filtered and evaporated completely to give crude compound. This crude obtained was purified by flash chromatography using 10% ethyl acetate in hexane as eluent to afford desired compound dimethyl 2-(4,4,5,5-tetramethyl-1 ,3,2-dioxaborolan-2- yl)benzene-1 ,4-dicarboxylate (15 g, 81 % of theoretical yield). H NMR (400 MHz, CHLOROFORM-c/) δ ppm 1.41 - 1.45 (m, 15 H) 3.94 (s, 6 H) 8.00 (s, 1 H) 8.05 - 8.13 (m, 1 H) 8.16 (s, 1 H) |
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With potassium acetate;(1,1'-bis(diphenylphosphino)ferrocene)palladium(II) dichloride; In 1,4-dioxane; at 80℃;Inert atmosphere; |
Step 2[00263] Bis-(pinacolato)diboron (4.93 g, 19.40 mmol), 1 , 1*-Bis(diphenyl phosphino)ferrocene]dichloropalladium (II) (0.72 g, 0.88 mmol), potassium acetate (5.19 g, 17.65 mmol) were dissolved in dioxane (40 ml) and flushed with argon. A solution of <strong>[18643-86-2]dimethyl 2-bromoterephthalate</strong> (CV) (4.82 g, 17.65 mmol) in dioxane (15 mL) was then added and the reaction mixture was heated at 80C overnight. The solids were filtered off and washed with EtOAc. The combined organic phases were concentrated under vacuum and the residue was dissolved in EtOAc, washed with water, dried over anhydrous MgS04 and concentrated to give 8.01 g of a black oil. The oil was purified by silica gel chromatography (DCM/MeOH 1000: 1→500: 1→200: 1→100: 1) to give dimethyl 2-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2- yl)terephthalate (CVI) (2.60 g, 8.12 mmol, 51% purity, 23% yield). ESIMS found for Ci6H2iB06 mlz 243.3 (M+Na). |