Benzene → L-Aspartic acid, 1,4-bis(phenylmethyl) ester, 4-methylbenzenesulfonate (1:1)

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Reaction Steps

A stirred mixture of L-aspartic acid (133 g.; 1.00 mole), benzyl alcohol (650 g.; 6.00 moles), p-toluenesulfonic acid monohydrate (194 g.; 1.02 moles), and dry benzene (400 ml.) was heated at reflux for 6.5 hours. Although benzene has been used, it is within the scope of the invention to employ other solvents such as, for example, toluene and tetrachloroethylene. The water formed in the reaction (46 ml.) was removed by means of a Dean-Stark trap. The resulting solution was cooled to room temperature then diluted with benzene (400 ml.) and ether (1200 ml.). On cooling to 10°, a white solid precipitated. This material was collected on a filter, washed with ether (1.0 l.), and dried; yield of crude (I), 384 g. (79%). A 304 g. portion of the product was recrystallized from methanol (425 ml.) to give 186 g. (61.2% recovery) of material suitable for further transformation; m.p., 155.5°-158°; literature m.p., 158°-160° .

Provenance & Evidence