Diisopropylethylamine → 1-[3-chlorophenyl(phenyl)carbamoyl]-4-dipentylcarbamoyl-(2S)-hexahydro-2-pyrazinecarboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a suspension of 1.05 g (2.3 mmole) of (S)-1-[N-(3-chlorophenyl)-N-phenylcarbamoyl]piperazine-2carboxylic acid hydrobromide (from Step C) in 20 ml of methylene chloride was added 1.23 g (9.5 mmole) of N,N-diisopropylethylamine followed by the dropwise addition of a solution of 523 mg (2.38 mmole) of dipentylcarbamoyl chloride (from Example 1, Step C-2) in 5 ml of methylene chloride. After stirring 24 hours at 25° C., the solution was extracted with 2N HCl, then H2O and dried over MgSO4. The dried methylene chloride solution was concentrated in vacuo and the residue was dissolved in isopropyl ether and was diluted with petroleum ether (bp. 30°-60° C.) until cloudy. The oil which precipitated was then decanted, redissolved in isopropanol and concentrated in vacuo to yield 464 mg (36%) of (S)-1-[N-(3-chlorophenyl)-N-phenylcarbamoyl]-4-(dipentylcarbamoyl)piperazine-2-carboxylic acid as a glassy solid; TLC showed a single spot, Rf 0.75 (Analtech SGF plates developed with isoamyl alcohol:acetone:water [5:2:1]).

Provenance & Evidence