Trifluoroacetic acid → HCID 59333345, compound

Participants

Reaction Steps

To a solution of 4-[4-(3-hydroxy-propylamino)-7-trifluoromethyl-imidazo[1,2-a]quinoxalin-1-yl]-3,6-dihydro-2H-pyridine-1-carboxylic acid tert-butyl ester (1.10 g; 2.30 mmol; 1 eq) in anhydrous dichloromethane (12 mL) is slowly added trifluoroacetic acid (1.77 mL; 23.0 mmol; 10 eq). The solution is allowed to stir for 6 hours at room temperature until completion of the reaction. The reaction mixture is concentrated and the residual traces of trifluoroacetic acid are removed by co-distillation with toluene (2×10 mL). The red gum is taken up in water (73 mL) and the resulting aqueous solution is washed with ethyl acetate (375 mL) before adjusting the pH to 8 by addition of sodium bicarbonate in powder. This basic aqueous layer is then extracted with ethyl acetate (5×100 mL). The organic extracts are combined, dried over sodium sulfate and concentrated in vacuum. The resulting crude residue is then passed through a silica gel column (ethyl acetate/methanol 8:2 then ethyl acetate/methanol/triethylamine 8:2:0.3) to afford the title compound still contaminated with minor impurities. The powder is then washed with ether to afford the title compound as an off-white solid (170 mg; 0.44 mmol; 19%)

Provenance & Evidence