Electric Literature of 31599-60-7, These common heterocyclic compound, 31599-60-7, name is 1-Iodo-2,3-dimethylbenzene, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.
To a solution of 1-iodo-2,3- dimethylbenzene (8) [prepared according to Chen, Y et al. Org. Lett. 2007, 9, 1899] (1 .93 g, 8.32 mmol) in carbon tetrachloride (40 mL) was added NBS (3.67 g, 20.62 mmol), AIBN (0.070 g, 0.43 mmol) and the resulting mixture was gently refluxed by irradiation with a halogen lamp (500 W) for 4 h. The precipitate was filtered and washed with a small amount of carbon tetrachloride. The filtrate was concentrated under reduce pressure, the obtained residue was dissolved in EtOAc ( 1 00 ml), successively washed with 10% NaOH solution (20 mL), water (2 x 20 ml), 10% Na2S203 solution (20 mL), water (20 mL), brine (20 raL), and dried (Na2SC>4). The solvent was evaporated and the residue was purified by column chromatography on silica gel (eluent petroleum ether) to give 1 .89 g (58.3%) of compound 9. NMR (CDC13) delta: 7.84 (dd, J=8.1 , 1 .1 Hz, 1 H), 7.33 (dd, J=7.6, 1 .1 Hz, l H), 6.97 (t, J=7.8 Hz, 1 H), 4.85 (s, 2H), 4.66 (s, 2H). The product contained ca. 15-20% of an inseparable impurity (supposedly l -bromo-2,3-bis(bromomethyl)benzene).A mixture of 1,2-bis(bromomethyl)-3-iodobenzene (9) (2.50 g, 6.41 mmol), diethyl 2-acetamidomalonate (1 .39 g, 6.41 mmol), and K2C03 (2.22 g, 1 6.06 mmol) in acetonitrile (40 mL) was refluxed for 70 h. The mixture was allowed to cool to ambient temperature, the precipitate was filtered and washed with a small amount of acetonitrile. The filtrate was concentrated under reduce pressure, the obtained residue was dissolved in EtOAc (100 mL), washed successively with saturated NaHC03 solution (30 mL), water (2 x 30 mL), brine (30 mL), and dried (Na2S04). The solvent was evaporated and the residue was purified by column chromatography on silica gel (eluent petroleum ether-ethyl acetate, gradient from 20: 1 to 20:6) to give 2 g of oil. The oil was dissolved in diethyl ether and kept in a refrigerator overnight. The precipitate was filtered and dried to give 0.4 g (14%) of a regioisomer diethyl 2-acetyl-5-iodo-l ,4-dihydroisoquinoline-3,3(2H)-dicarboxylate. NMR (CDC13) delta: 7.76 (d, J=8.0 Hz, 1H), 7.13 (d, J=7.5 Hz, 1 H), 6.94 (t, J = 7.7 Hz, 1H), 4.65 (s, 2H), 4.19 (q, J=7.1 Hz, 2H), 4.16 (q, J=7.1 Hz, 2H), 3.56 (s, 2H), 2.28 (s, 3H), 1 .22 (t, J=7.1 Hz, 3H), 1.22 (t, J=7.1 Hz, 3H). LCMS (ESI) m/z: 446 [M+H]+. The filtrate was evaporated and the residue was purified by column chromatography on silicagel (eluent petroleum ether-ethyl acetate, gradient from 20: 1 to 20:6) to give 0.95 g (33.2%) of compound (10).A solution of diethyl 2-acetyl-8-iodo-l,4-dihydroisoquinoline-3,3(2H)-dicarboxylate (10) (0.585 mmol) in 6 N HQ (10 mL) was refluxed for 5 h. The mixture was cooled and cone. NH4OH water solution was added until pH of the medium was ~7. The precipitate was filtered, washed with a small amount of water, and dried to give 0.305 g (76.7%) of compound (11). Because of a low solubility of the product in common deuterated organic solvents and deuterium oxide, the NMR spectrum was not informative. LCMS (ESI) m/z: 304 [M+H]+. The product contained ca. 15-20% of an inseparable impurity (supposedly the corresponding bromo derivative 8-bromo-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid). LCMS (ESI) m/z: 256 [M+H]+.To a suspension of 8-iodo-l ,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (11) (0.645 g, 2.13 mmol) in methanol ( 1 8 mL) slowly SOCI2 ( 1.07 ml, 14.92 mmol) was added within 10 min. The reaction mixture was stirred at room temperature for 16 h, evaporated, and the residue was dissolved in a mixture of IN NaHC03 solution (30 mL) and EtOAc (50 mL). The organic layer was separated and the aqueous layer was extracted with EtOAc (2 ^ 15 mL). The organic extracts were combined, washed successively with water (20 mL), brine (20 mL), and dried (Na2S04). The solvents were evaporated to give compound 12 (0.570 g, 84%) which was used in the next step without further purification. NMR (CDCI3) delta: 7.67 (d, J=7.8 Hz, IH), 7.10 (d, J=7.5 Hz, I H), 6.87 (t, J=7.7 Hz, IH), 4.07 (d, 16.6 Hz, IH), 3.87 (d, J=16.6 Hz, I H), 3.78 (s, 3H), 3.71 (dd, J=9.4, 5.0 Hz, I H), 3.04 (dd, J=16.5, 5.0 Hz, IH), 2.97 (dd, J=l 6.5, 9.4 Hz, IH). LCMS (ESI) m/z: 318 [M+H]+. The product contained ca. 15-20% of an inseparable impurity (supposedly the corresponding bromo derivative methyl 8-bromo-1,2,3,4-tetrahydroisoquinoline-3-carboxylate). LCMS (ESI) m/z: 270 [M+H]+.A mixture of methyl 8-iodo-1, 2,3,4- tetrahydroisoquinoline-3-carboxylate (12) (0.570 g, 1 .8 mmol) and 2,3-dichloro-5,6-dicyano- 1 ,4-benzoquinone (DDQ) (0.449 g, 2.0 mmol) in toluene (20 mL) was refluxed for 6 h. To the reaction mixture was added another portion of DDQ (0.100 g, 0.45 mmol) and the refluxing was continued for 16 h. The mixture was allowed to cool to room temperature; the precipitate was filtered and washed with a small amount of toluene. The filtrate was evaporated and the residue was purified by column chromatography on silicagel (eluent petroleum ether-ethyl acetate, gradient from 100:0 to 100: …
The synthetic route of 31599-60-7 has been constantly updated, and we look forward to future research findings.
Reference:
Patent; LATVIAN INSTITUTE OF ORGANIC SYNTHESIS; JIRGENSONS, Aigars; LOZA, Einars; CHARLTON, Michael; FINN, Paul William; RIBAS DE POUPLANA, Lluis; SAINT-LEGER, Adelaide; (76 pag.)WO2016/129983; (2016); A1;,
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