Dicyclohexylcarbodiimide → N,N'-Dicyclohexylurea

Participants

Reaction Steps

To a stirred solution of glyoxylic acid monohydrate (431 mg, 4.56 mmol) in anhydrous DMF (5 mL) were added NHS (563 mg, 4.89 mmol) and DCC (1.00 g, 4.85 mmol). A white solid (dicyclohexylurea) formed immediately. As the reaction was exothermic, the flask was cooled in an ice-bath for a while (approximately 5 minutes). The reaction mixture was then stirred under nitrogen at room temperature for approximately 1 hour. The solid was filtered off and washed with DMF. The filtrate (containing glyoxylic acid NHS ester) was then added to the reaction mixture obtained above. After stirring the mixture for approximately 5 minutes, a clear solution was obtained. TLC revealed completion of the reaction. The solvent was removed under reduced pressure. Flash chromatography (20:1 and 15:1 CH2Cl2—CH3OH followed by 20:1, 15:1 and 12:1 CH2Cl2—CH3OH containing 1% acetic acid) provided the desired Pro4-de novo-CHO (132 mg, 55%). The mass spectrum was in agreement with the assigned structure.

Provenance & Evidence