1,2-Dichloroethane → Propionic anhydride

Participants

Reaction Steps

A representative procedure was as follows: A solution of propionic anhydride was prepared in situ by reacting propionic acid (0.48 g, 6.5 mmol) with EDC (614 mg, 3.2 mmol) in acetonitrile for 15 min at room temperature. This solution was then added over the course of 5 min to a magnetically stirred solution of N-ε-benzyloxycarbonyl lysine (Lys(Cbz)) (1 g, 3.6 mmol) in 36 mL 0.1 M NaOH and 20 mL 2-propanol. A fine white precipitate formed, another 36 mL 0.1 M NaOH was added, and stirring was continued overnight. The reaction mixture was then concentrated in vacuo to remove the organic solvents and acidified to a pH of 2.5 with 1M HCl. During acidification, the white precipitate dissolved. The aqueous solution was extracted with chloroform and then ethyl acetate. These organic solvents were combined and concentrated on the rotary evaporator to yield a colorless oil which was used without purification in the next step.

Provenance & Evidence