5-FLUOROINDOLE-3-CARBOXALDEHYDE

General procedure: Phosphorus oxychloride (0.42 g, 2.74 mmol) was added dropwise to a solution of the indole 5b, 5e–5g (0.30 g, 2.29 mmol) in DMF (0.84 g, 11.4 mmol) at 0 °C for 30 min. The solution was then heated at 40 °C for 1 h. Ice was added to the reaction vessel, followed by a solution of sodium hydroxide (2 M). The solution was refluxed for 40 min. The mixture was cooled and extracted using ethyl acetate, and the organic phase was washed with brine. The organic extracts were combined, dried over NaTo 3 mL of DMF was added phosphoryl chloride (2.04 g, 13.3 mmol) dropwise at 0 °C. The mixture was stirred for half an hour, then a solution of 5-fluoroindole (1.5 g, 11.1 mmol) in 2 mL of DMF was added dropwize into the mixture. The resulting mixuture was heated to 25 °C and reacted for 24 hours. The reaction mixture was quenched with 30 mL of water and neutralized with sodium carbonate solid to the pH=8-9. The mixture was filtered and the filter cake was dried in vacuo to give the title compound as a yellow solid (1.56 g, 86percent). The compound was characterized by the following spectroscopic data: MS (ESI, pos. ion) m/z: 164.1 [M+Hfb; and ‘H NMR (400 MHz, DMSO-d6): 6 9.93 (s, 1H), 8.35 (s, 1H), 7.77 (dd, J = 9.6, 2.6 Hz, 1H), 7.54J 8.9, 4.6 Hz, 1H), 7.12 (td, J 9.2, 2.6 Hz, 1H).General procedure: To a dried two-neck round-bottom flask containing DMF (0.7mL for 1.10mmol of starting material) chilled in an ice bath, POClGeneral procedure: Under air, a 20 mL of Schlenk tube equipped with a stir bar was charged with indole 1 (0.2 mmol, 1 equiv), TMEDA (75 µL, 0.5 mmol, 2.5 equiv), NaGeneral procedure: A method for synthesizing compound III-1 wherein R1, R2 and R3 are simultaneously hydrogen in the formula III, the method comprising the steps of:(1) Add to a 50 mL round bottom flask1.0mmol indole(In the formula I, R1, R2, and R3 are both hydrogen) and1.0 mmol (0.140 g) of hexamethylenetetramine, then 2 mL of N, N-dimethylformamide (DMF), stirred in a magnetic stirrer to dissolve the solid, followed by the addition of 0.05 mmol (0.012 g) of crystalline trichloride Aluminum, connected to a reflux condenser, heated at 120 ° C, the reaction progress was monitored by TLC, and the reaction was cooled to room temperature after 1 h to prepare a suspension;(2) The suspension prepared in the step (1) is suction filtered with a funnel padded with diatomaceous earth.The filter cake was washed well with ethyl acetate, suction filtered, and the above operation was repeated until the filtrate had no product, and all the filtrates were combined.Dilute with 15 mL of saturated saline solution, disperse and separate the layers, and the aqueous layer was further extracted with ethyl acetate three times.Each time 10 mL, the ethyl acetate layer was combined and washed with 10 mL of 2 mol/L diluted hydrochloric acid.Wash with 10 mL of saturated sodium bicarbonate solution, and finally wash with 10 mL of saturated brine.The washed ethyl acetate layer was dried over anhydrous sodium sulfate, and after drying, the desiccant was filtered off.Then use a rotary evaporator to recover the solvent to concentrate the product, and finally, The residue is subjected to silica gel column chromatography using a mixture of n-hexane-ethyl acetate (V/V = 2:1) as an eluent to obtain a purified product.The mass of the compound III-indole-3-carbaldehyde is 0.137g, The product yield was 94percent.General procedure: A 50 mL round-bottomed flask equipped with a magnetic stirringbar was charged with the appropriate indole 1 (0.5 mmol, 1.0 equiv), 37percent aq HCHO (0.5 mmol, 0.0406 g, 1.0 equiv), 25percent aqNH3 (1.0 mmol, 0.0681 g, 2.0 equiv), FeCl3 (0.01 mmol, 0.0016 g, 2 molpercent), and DMF (2 mL). The flask was fitted with a reflux condenser, and the mixture was stirred at 130 °C under open air.When the reaction was complete (TLC), the mixture was cooledto r.t., diluted with sat. aq NaCl (10 mL) and 0.5 M aq HCl (2 mL), and extracted with EtOAc (3 x 7 mL). The organic layers werecombined, washed with sat. aq NaHCO3 (10 mL) and sat. aq NaCl(10 mL), dried (Na2SO4), and concentrated under reduced pressure.The residue was purified by flash column chromatography(silica gel, hexane–EtOAc).

Molecular Weight:163.15
XLogP3:1.8
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:2
Rotatable Bond Count:1
Exact Mass:163.043341977
Monoisotopic Mass:163.043341977
Topological Polar Surface Area:32.9
Heavy Atom Count:12
Complexity:185
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes