| 74% |
With trichlorophosphate at 80 - 90℃; for 12h; |
General procedure for synthesis of 2-chloroquinoline-3-carbaldehydes 3
To stirred DMF (3.6 mL, 46 mmol), 12.5 mL POCl3 (134 mmol) were added dropwise at 0-5 °C. The mixture was allowed to stir for 30 min. Acetanilide 2 (18.5 mmol) was then added and the resulting solution heated for 12 h at 80-90 °C. The mixture was poured into ice-cold water and stirred for 10 min, which resulted in yellow precipitation of the desired 2-chloroquinoline-3-carbaldehydes 3. The precipitate was filtered and washed with water and then dried. The compounds were purified by recrystallization from ethyl acetate. |
| 68% |
With trichlorophosphate In 1,2-dichloro-ethane at 40℃; for 1h; ultrasound irradiation; |
|
| 60% |
Stage #1: 4-bromoacetanilide; N,N-dimethyl-formamide With trichlorophosphate at 75℃; for 48h; Inert atmosphere;
Stage #2: With water |
|
| 45% |
With trichlorophosphate at 85℃; for 24h; |
|
| 35% |
With trichlorophosphate at 80 - 90℃; for 16h; |
|
| 35% |
With trichlorophosphate at 0 - 80℃; for 16h; |
|
| 28% |
Stage #1: N,N-dimethyl-formamide With phosphorus pentachloride at 0℃; for 0.25h;
Stage #2: 4-bromoacetanilide for 4h; Reflux; |
Synthesis of 2-chloroquinoline-3-carbaldehydes 5a-i
General procedure: Dimethylformamide (12 mmol, 3 equiv.) was cooled at 0°C in a round flask equipped with a drying tube and phosphorus pentachloride (18 mmol, 4.5 equiv.) was added slowly and the mixture was stirred for 15 minutes keeping the temperature below 0°C. To this solution was added in a portion the corresponding acetanilide (4 mmol, 1 equiv.) and the reaction mixture was heated under reflux and stirring for the appropiate time depending of the acetanilide. The resulted mixture was cooled to 0°C and the solution was poured slowly into ice-water and stirring for ten minutes, obtaining a yellow solid which was filtered, washed several time with cold water and dried under vacuum. The 2-chloroquinoline-3-carbaldehydes were recrystallized according to the literature. |
| 27% |
Stage #1: N,N-dimethyl-formamide With trichlorophosphate at -5℃; Inert atmosphere;
Stage #2: 4-bromoacetanilide at 80℃; Inert atmosphere; |
5.2.1. 2-chloroquinoline-3-carbaldehyde (2a)
General procedure: Phosphorus oxychloride (19 ml, 207.16 mmol) was added drop wise at -5°C to DMF (7 ml, 88 mmol) under N2, then the acetanilide 1a(4.000 g, 29.59 mmol) was added at room temperature. The mixture was stirred overnight at 80 °C, then slowly poured on ice, filtered and dried to obtain compound 2a as light yellow solid; yield (5.100 g, 90%)Rf (15% EtOAc/Hexane)- 0.56. |
|
Stage #1: N,N-dimethyl-formamide With trichlorophosphate at 0℃;
Stage #2: 4-bromoacetanilide for 16h; Heating; |
|
|
With trichlorophosphate at 75℃; for 48.5h; Inert atmosphere; Sealed tube; Cooling with ice; |
II.1
Step 1; DMF (54 ml, 701 mmol, 2.5 eq.) was added dropwise (via a syringe pump) to phosphoryl trichloride (179 ml, 1962 mmol, 7.0 eq.) in a 350 mL sealed tube in an ice bath under nitrogen. After the addition, the water bath was removed and N-(4-bromophenyl) acetamide (60 g, 280 mmol) was added in one portion and the resulting mixture was stirred until a homogenous solution was observed (approx. 30 min.). The reaction vessel was sealed and heated at 75 °C for 48 h. The reaction was allowed to cool and slowly poured onto ice (final volume of 2 L) and stirred for 25 min. The solid was filtered and washed with water until the filtrate was no longer acidic (~3 L) and the product was dried in an oven vacuum overnight at 50 °C to afford a light tan/gold colored solid, 6-bromo-2- chloroquinoline-3 -carbaldehyde. |
|
Stage #1: N,N-dimethyl-formamide With trichlorophosphate Cooling with ice; Sealed tube; Inert atmosphere;
Stage #2: 4-bromoacetanilide at 75℃; for 48.5h;
Stage #3: With water Cooling with ice; |
7.3
Step 3: MN-dimethylformamide (54 ml, 0.70 mol) was added dropwise (via a syringe pump) to phosphoryl trichloride (179 ml, 1.96 mol) in a 350 mL sealed tube in an ice bath under nitrogen. After the addition, the water bath was removed and N-(4- bromophenyl)acetamide (60 g, 0.28 mol) was added in one portion and stirred until a homogenous solution was observed (approx. 30 min.). The reaction vessel was sealed and heated at 75 °C for 48 h. The reaction was allowed to cool and slowly poured onto ice (final volume of 2 L) and stirred for 25 min. The solid was filtered and washed with water until the filtrate was no longer acidic (~3 L) and the product was dried in an oven vacuum overnight at 50 °C to afford 6-bromo-2-chloroquinoline-3-carbaldehyde as a light tan colored solid. |
|
With trichlorophosphate |
|
|
With trichlorophosphate at 0℃; Reflux; |
General procedure for the synthesis of 6-substituted-2-chloroquinoline-3-carbaldehydes 2a-d (Meth-Cohnet al., 1981)
General procedure: Dimethylformamide 9.6 mL (0.125 mol)was cooled to 0 C, and phosphoryl chloride 32.2 mL(0.35 mol) was added drop-wise with stirring. To thissolution was added substituted acetanilide 1a-d (0.05 mol)and the reaction mixture was refluxed for 16-17 h. Reactioncompletion was monitored by TLC. The reactionmixture was poured into ice water (300 mL) and stirred for30 min at 0-10 °C. The resulting suspension was filteredand washed with water to give the intermediates 2a-d. |
|
With trichlorophosphate |
|
|
With trichlorophosphate for 24h; Heating; |
|
|
With trichlorophosphate at 70 - 80℃; for 16h; |
Preparation of 2-chloroquinolin-3-carbaldehyde (6c-i)
General procedure: Vilsmeir-Haack adduct was prepared by adding phosphorous oxychloride (0.35 mol) drop wise to the cold solution of DMF (0.125 mol) with constant stirring. To this adduct, substituted acetanilide (0.05 mol) was added slowly and stirred well for 15-20 min. The mixture was then refluxed for 16 h at 70-80°C. After completion of the reaction, the contents were poured into ice water and stirred for 30 min. The 2-chloroquinoline-3-carbaldehyde 6c-i precipitated out was filtered and washed well with water. Dried and recrystallized from ethyl acetate. |
|
Stage #1: N,N-dimethyl-formamide With trichlorophosphate at 0℃; for 0.25h;
Stage #2: 4-bromoacetanilide at 80℃; for 8h; |
|
|
With trichlorophosphate for 6h; Reflux; |
|
|
With trichlorophosphate at 80 - 90℃; |
|
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