Triethylamine → (S)-4-(Benzyloxycarbonyl)-1-(diphenylacetyl)piperazine-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 1.00 g (3.78 mole) of (S)-4 -(benzyloxycarbonyl)piperazine-2-carboxylic acid (from Example 7, Step A) in 10 ml of DMF at 25° C. was treated with 0.755 g. (7.46 mmole) of triethylamine. The solution was cooled to 0° C. and 0.95 g (4.12 mmole) of diphenylacetyl chloride was added in portions over 2 hours. The solution was stirred at 25° C. for 64 hours, concentrated in vacuo and partitioned between 60 ml. of 1N HCl and 60 ml of ethyl acetate. The ethyl acetate was dried over sodium sulfate, concentrated in vacuo and chromatographed in two portions over an 85×2.5 cm LH-20 column with 11 ml fractions of methanol. Fractions 38-41 from both columns were combined and concentrated in vacuo to 785 mg (44%) of oil which was homogeneous by TLC (80:20:2 chloroform-methanol-ammonia water, Rf =0.40).

Provenance & Evidence