HCID 56625303, compound → HCID 56639309, compound

Participants

Reaction Steps

A solution of 5.18 g of tert.-butyl (3S)-2-(3-benzoylthio-2-methylpropionyl)-1,2,3,4-tetrahydroisoquinoline-3-carboxylate in 20 ml of trifluoroacetic acid is allowed to stand at room temperature for one hour. The reaction solution is distilled under reduced pressure to remove solvent. Ethyl acetate and an aqueous sodium bicarbonate solution is added to the residue. After shaking the mixture, the aqueous layer is collected therefrom and is made acidic with diluted hydrochloric acid. Then, the aqueous solution is extracted with ethyl acetate. The extract is washed with water, dried and then distilled to remove solvent. 4.4 g of (3S)-2-(3-benzoylthio-2-methylpropionyl)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid are thereby obtained as pale yellow oil. Yield: 97.2 % 4.4 g of this product are dissolved in about 20 ml of ether, and 2.1 g of dicyclohexylamine are added thereto. Said mixture is distilled to remove ether. After the residue is washed with n-hexane, ether is added to said residue. Crystalline precipitates are collected by filtration, whereby 2.15 g of (3S)-2-[(2S)-3-benzoylthio-2-methylpropionyl]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid.dicyclohexylamine salt are obtained as colorless crystals. Yield: 32.2 % M.p. 164°-166° C.(recrystallized from ethyl acetate-ether)

Provenance & Evidence