2-(Ethylsulfonyl)ethanol → 4-[2-(Ethylsulfonyl)ethyl]-1-piperazinecarboxylic acid, phenylmethyl ester

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Reaction Steps

To a solution of 6.6 g (0.03 mole) of 1-piperazinecarboxylic acid, phenylmethyl ester in 100 ml of N,N-dimethylformamide was added, in portions, 1.44 g (0.03 mole) of a 50% sodium hydride suspension in mineral oil. The mixture was heated at 50° for 1 hr and allowed to cool slightly. To it was added dropwise a solution of 8.8 g (0.003 mole) of 2-(ethylsulfonyl)ethanol, 4-methylbenzenesulfonate in 30 ml of N,N-dimethylformamide. The mixture was heated at 50° for 1 hr, allowed to cool, concentrated under vacuum to one-half the original volume, allowed to stand for four days and then concentrated to a paste. The paste was diluted with ether and the suspension filtered to remove insoluble salts. The filtrate was concentrated and chromatographed over 250 g of silica gel with 1 l each of the following solutions of methanol in ethyl acetate: 1.5%, 3% and 15%. That portion of the eluent containing the product, Rf(silica--10 % methanol/ethyl acetate)=0.7, was concentrated to dryness under vacuum to afford 8.3 g (81%) of the desired product as an oil. The IR and NMR spectra were consistent with the assigned structure.

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