4-Toluenesulfonyl chloride → (S)-2-(Methylamino)-2-oxo-1-phenylethyl 4-methylbenzenesulfonate

Reaction equation

[C:1]([NH2:11])(=[O:10])[CH:2]([C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1)[OH:3].[CH2:12](N(C(C)C)C(C)C)C.[C:21]1([CH3:31])[CH:26]=[CH:25][C:24]([S:27](Cl)(=[O:29])=[O:28])=[CH:23][CH:22]=1>ClCCl>[CH3:12][NH:11][C:1]([C@@H:2]([O:3][S:27]([C:24]1[CH:25]=[CH:26][C:21]([CH3:31])=[CH:22][CH:23]=1)(=[O:29])=[O:28])[C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1)=[O:10]

Participants

Procedure

To the solution of mandelic acid amide in dichloromethane is added N-ethyldiisopropylamine (1.1 equivalents) at RT. Subsequently p-toluene sulfonic acid chloride (1.0 equivalent) is added keeping the temperature below 25° C. The reaction mixture is stirred at RT until a satisfactory conversion is reached and then washed with saturated sodium bicarbonate solution and water. After a solvent switch to ethyl acetate the solution is concentrated, cooled to −2° C. and the precipitate filtered. The crystals are washed with cooled ethyl acetate and dried in vacuo at 40° C.