Triethylamine → 4-[4-(4-(ethenesulphonyl)piperazin-1-yl)phenyl]-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester

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Reaction Steps

2 g of 4-(4-(piperazin-1-yl)phenyl)-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester are placed in a 250 ml round-bottomed flask under an inert atmosphere. 72 ml of anhydrous dichloromethane are added and then, at 0° C., 1.22 ml of chloroethylsulphonyl chloride are added, followed by 3.67 ml of triethylamine. The reaction mixture is allowed to return gently to ambient temperature. The reaction mixture is stirred at ambient temperature for 3 h before being diluted with dichloromethane. The organic phase is washed with a saturated aqueous sodium hydrogencarbonate solution and the aqueous phase is extracted with dichloromethane. The organic phases are combined and washed with water, then dried over sodium sulphate, filtered through a sintered glass filter and concentrated under reduced pressure. 1.01 g of 4-[4-(4-(ethenesulphonyl)piperazin-1-yl)phenyl]-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester are obtained in the form of a white solid, after purification on a silica column, elution being carried out with a heptane/ethyl acetate gradient varying from 95/5 to 40/60.

Provenance & Evidence