p-Toluenesulfonic acid → N-[[N-[N-(benzyloxycarbonyl)-L-alanyl]-L-phenylalanyl]-methyl]-L-proline tert.butyl ester

Participants

Reaction Steps

1.3 g (2.79 mmol) of N-[[N-(benzyloxycarbonyl)-L-phenylalanyl]methyl]-L-proline tert.butyl ester was hydrogenated in a mixture of 10 ml of ethyl acetate and 10 ml of isopropyl alcohol in the presence of 0.39 g of 5% palladium-on-carbon and 1.06 g (5.58 mmol) of toluene-4-sulphonic acid and the product was coupled with 0.62 g (2.78 mmol) of N-(benzyloxycarbonyl)-L-alanine in the presence of 0.572 g (2.78 mmol) of dicyclohexylcarbodiimide, 0.375 g (2.78 mmol) of hydroxybenzotriazole and 0.64 g (5.57 mmol) of N-ethylmorpholine in a manner analogous to that described in Example 1. After working-up and chromatography on silica gel using 3% isopropanol in dichloromethane for the elution there was obtained 0.55 g of N-[[N-[N-(benzyloxycarbonyl)-L-alanyl]-L-phenylalanyl]methyl]-L-proline tert.butyl ester as a solid: MS: m/e 538 [M+H]+.

Provenance & Evidence