2,4-DIMETHOXY-BENZENEACETIC ACID METHYL ESTER

To a stirred solution of acid 9 (320 mg, 1.76 mmol) in CH2Cl2 (10 mL) under N2 atmosphere, DMF (one drop) and oxalyl chloride (0.23 mL, 2.6 mmol) were added. The mixture was stirred for 3 h at room temperature and then the solvent was removed under vacuum. The crude product acid chloride was directly used for the next reaction without further purification. A solution of compound 1114 (554 mg, 2.64 mmol) in THF (6 mL) was added at -78 C to a freshly prepared solution of LDA, prepared from n-BuLi (2.5 M in THF, 1.44 mL, 3.52 mmol) and i-Pr2NH (0.49 mL, 3.52 mmol) in THF (5 mL) at 0 C under N2 atmosphere. The thus produced yellowish anion was stirred at -78 C for 45 min and then a solution of crude acid chloride in THF (10 mL) was added drop wise. The reaction was stirred at the same temperature for another 45 min and then at room temperature for 4 h. 10% HCl (10 mL) was added to quench the reaction, THF was removed in vacuum and the water layer was extracted with ethyl acetate (2*50 mL). The organic layer was washed with water (2*20 mL), brine (20 mL), dried (Na2SO4) and concentrated. The crude product was purified by silica gel column chromatography to get 12 (500 mg, 76%) as yellowish oily compound. Rf 0.3 (1:1 ethyl acetate:hexane); 1H NMR (CDCl3, 500 MHz): delta 7.89 (d, 1H, J=9.0Hz, C6?-H), 7.03 (d, 1H, J=8.5Hz, C6?-H), 6.49 (dd, 1H, J=9.0, 2.0Hz, C5?-H), 6.44 (s, 1H, C3?-H), 6.41 (d, 1H, J=8.5Hz, C5?-H), 6.36 (d, 1H, J=2.0Hz, C3?-H), 5.95 (s, 1H, C2-H), 3.78 (s, 3H, OMe), 3.75 (s, 3H, OMe), 3.74 (s, 3H, OMe), 3.73 (s, 3H, OMe), 3.72 (s, 3H, CO2Me); 13C NMR (CDCl3, 125 MHz): delta 193.1 (C), 171.0 (C), 164.9(C), 160.7 (C), 160.3(C), 157.9 (C), 133.5 (CH), 130.3 (CH), 119.5 (C), 115.6 (C), 105.7 (CH), 104.2 (CH), 98.5 (CH), 98.0 (CH), 57.2 (CH3), 55.5 (CH3), 55.5 (CH3), 55.2 (CH3), 55.2 (CH3), 52.2 (CH); HRMS (EI+) m/z 374.1370 ([M]+ C20H22O7, requires 374.1366).21A was prepared analogously to compound 12A. Quantitative yield. MS: 211 (M+1)+.General procedure: To a stirred solution of acid 9 (320 mg, 1.76 mmol) in CH2Cl2 (10 mL) under N2 atmosphere, DMF (one drop) and oxalyl chloride (0.23 mL, 2.6 mmol) were added. The mixture was stirred for 3 h at room temperature and then the solvent was removed under vacuum. The crude product acid chloride was directly used for the next reaction without further purification. A solution of compound 1114 (554 mg, 2.64 mmol) in THF (6 mL) was added at -78 C to a freshly prepared solution of LDA, prepared from n-BuLi (2.5 M in THF, 1.44 mL, 3.52 mmol) and i-Pr2NH (0.49 mL, 3.52 mmol) in THF (5 mL) at 0 C under N2 atmosphere. The thus produced yellowish anion was stirred at -78 C for 45 min and then a solution of crude acid chloride in THF (10 mL) was added drop wise. The reaction was stirred at the same temperature for another 45 min and then at room temperature for 4 h. 10% HCl (10 mL) was added to quench the reaction, THF was removed in vacuum and the water layer was extracted with ethyl acetate (2*50 mL). The organic layer was washed with water (2*20 mL), brine (20 mL), dried (Na2SO4) and concentrated. The crude product was purified by silica gel column chromatography to get 12 (500 mg, 76%) as yellowish oily compound.General procedure: To a stirred solution of acid 9 (320 mg, 1.76 mmol) in CH2Cl2 (10 mL) under N2 atmosphere, DMF (one drop) and oxalyl chloride (0.23 mL, 2.6 mmol) were added. The mixture was stirred for 3 h at room temperature and then the solvent was removed under vacuum. The crude product acid chloride was directly used for the next reaction without further purification. A solution of compound 1114 (554 mg, 2.64 mmol) in THF (6 mL) was added at -78 C to a freshly prepared solution of LDA, prepared from n-BuLi (2.5 M in THF, 1.44 mL, 3.52 mmol) and i-Pr2NH (0.49 mL, 3.52 mmol) in THF (5 mL) at 0 C under N2 atmosphere. The thus produced yellowish anion was stirred at -78 C for 45 min and then a solution of crude acid chloride in THF (10 mL) was added drop wise. The reaction was stirred at the same temperature for another 45 min and then at room temperature for 4 h. 10% HCl (10 mL) was added to quench the reaction, THF was removed in vacuum and the water layer was extracted with ethyl acetate (2*50 mL). The organic layer was washed with water (2*20 mL), brine (20 mL), dried (Na2SO4) and concentrated. The crude product was purified by silica gel column chromatography to get 12 (500 mg, 76%) as yellowish oily compound.General procedure: To a stirred solution of acid 9 (320 mg, 1.76 mmol) in CH2Cl2 (10 mL) under N2 atmosphere, DMF (one drop) and oxalyl chloride (0.23 mL, 2.6 mmol) were added. The mixture was stirred for 3 h at room temperature and then the solvent was removed under vacuum. The crude product acid chloride was directly used for the next reaction without further purification. A solution of compound 1114 (554 mg, 2.64 mmol) in THF (6 mL) was added at -78 C to a freshly prepared solution of LDA, prepared from n-BuLi (2.5 M in THF, 1.44 mL, 3.52 mmol) and i-Pr2NH (0.49 mL, 3.52 mmol) in THF (5 mL) at 0 C under N2 atmosphere. The thus produced yellowish anion was stirred at -78 C for 45 min and then a solution of crude acid chloride in THF (10 mL) was added drop wise. The reaction was stirred at the same temperature for another 45 min and then at room temperature for 4 h. 10% HCl (10 mL) was added to quench the reaction, THF was removed in vacuum and the water layer was extracted with ethyl acetate (2*50 mL). The organic layer was washed with water (2*20 mL), brine (20 mL), dried (Na2SO4) and concentrated. The crude product was purified by silica gel column chromatography to get 12 (500 mg, 76%) as yellowish oily compound.This compound was prepared from compound 8 in three steps without purifying the intermediate acid and acid chloride. n-BuLi (2.5 M in THF, 0.87 mL, 2.18 mmol) was added drop wise to a stirred solution of 8 (420 mg, 1.82 mmol) in THF (10 mL) at -78 C under N2 atmosphere. After 30 min CO2 gas was passed through the solution during 45 min of time and the mixture was allowed to warm up to room temperature. THF was removed in vacuum and the mixture was treated with saturated NaHCO3 solution (30 mL). The water layer was washed with ethyl acetate (2*15 mL) and then acidified with conc. HCl. The mixture was extracted with ethyl acetate (2*50 mL). The organic layer was washed with water (2*20 mL), brine (20 mL), dried (Na2SO4), filtered and concentrated to get the acid 10 (320 mg). Without further purification it was dissolved in CH2Cl2 (10 mL) under N2 atmosphere, DMF (one drop) and oxalyl chloride (0.23 mL, 2.6 mmol) were added. The mixture was stirred for 3 h at room temperature and then the solvent was removed in vacuum to yield the corresponding acid chloride, which was again directly used for the next reaction without further purification. A solution of compound 1114 (514 mg, 2.45 mmol) in THF (7 mL) was added at -78 C to a freshly prepared solution of LDA, prepared from n-BuLi (2.5 M in THF, 1.3 mL, 3.26 mmol) and i-Pr2NH (0.45 mL, 3.26 mmol) in THF (5 mL) at 0 C under N2 atmosphere. The thus produced yellowish anion was stirred at -78 C for 45 min and then a solution of crude acid chloride, prepared earlier, in THF (10 mL) was added drop wise. The reaction was stirred at the same temperature for another 45 min and then at room temperature for 4 h. 10% HCl (10 mL) was added to quench the reaction, THF was removed in vacuum and the water layer was extracted with ethyl acetate (2*50 mL). The organic layer was washed with water (2*20 mL), brine (20 mL), dried (Na2SO4) and concentrated. The crude product was purified by silica gel column chromatography to get 13 (480 mg, 68% in three steps) as yellowish oily compound. Rf 0.5 (1:1 ethyl acetate:hexane); numax (CHCl3) cm-1 1732, 1659, 1608, 1508, 1463, 1211, 1029; 1H NMR (CDCl3, 500MHz): delta 7.71 (s, 1H, C6?-H), 7.01 (d, 1H, J=8.5Hz, C6?-H), 6.43 (s, 1H, C3?-H), 6.41 (d, 1H, J=8.5Hz, C5?-H), 6.28 (s, 1H, C3?-H), 5.94 (s, 1H, C2-H), 3.82 (s, 3H, OCH3), 3.76 (s, 3H, OCH3), 3.75 (s, 3H, OCH3), 3.74 (s, 3H, OCH3), 3.71 (s, 3H, CO2CH3), 2.10 (s, 3H, CH3); 13C NMR (CDCl3, 125MHz): delta 193.1 (C), 171.1 (C), 163.0 (C), 160.3 (C), 159.6 (C), 157.9 (C), 133.1 (CH), 130.1 (CH), 118.9 (C), 118.0 (C), 115.8 (C), 104.1 (CH), 98.4 (CH), 94.1 (CH), 57.2 (CH3), 55.5 (CH3), 55.3 (CH3), 55.2 (CH3), 55.2 (CH3), 52.1 (CH), 15.3 (CH3); HRMS (EI+) m/z 388.1529 ([M]+ C21H24O7, requires 388.1521).

Molecular Weight:210.23
XLogP3:1.7
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:5
Exact Mass:210.08920892
Monoisotopic Mass:210.08920892
Topological Polar Surface Area:44.8
Heavy Atom Count:15
Complexity:205
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes