Piperazine → 2-(3-Benzoylthio-2-methylpropanoyl)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of (-)1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (5.0 g., 0.028 M) and sodium hydroxide (1.12 g., 0.028 M) in water (100 ml.) at 10° C. was slowly added (-)3-benzoylthio-2-methylpropionyl chloride (6.82 g., 0.028 M). At the same time, from a separate dropping funnel, was added a solution of sodium hydroxide (1.12 g., 0.028 M) in water (20 ml.), at such a rate that the solution was maintained at a pH between 9.5 and 7.5 pH units (final pH 7.5). After stirring overnight at 5° C., the reaction mixture was filtered and the clear filtrate acidified with dilute hydrochloric acid. The product was extracted into methylene dichloride, washed and dried over sodium sulfate. After filtration the solvent was removed by evaporation at reduced pressure, leaving a residue (8 g.). To a solution containing 0.5 g of this material in methylene dichloride was added piperazine (0.058 g., 0.67 mM). The solvent was removed and the product recrystallized from acetonitrile, giving a white solid, the title compound, as a hemipiperazine salt, m.p. 154°-155° C.

Provenance & Evidence