4-Toluenesulfonyl chloride → N-(toluene-4-sulfonyl)-N-methylphenylalanine

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Reaction Steps

N-Methyl-L-phenylalanine (500 mg, 2.79 mmol) was dissolved in 1N NaOH (6 mL). Dioxane (9 mL)) was added, followed by p-toluenesulfonyl chloride (532 mg, 2.79 mmol) and the mixture was vigorously stirred for 1 hr. The volatiles were removed in vacuo and the residue was dissolved in water (30 mL) and washed with Et2O (2×30 mL) before making acidic with 1N HCl. The mixture was extracted with CHCl3 (3×30 mL) and the extracts were evaporated in vacuo to give N-(toluene-4-sulfonyl)-N-methylphenylalanine as a solid (424 mg, 45%). N-(Toluene-4-sulfonyl)-N-methylphenylalanine was coupled to L-phenylalanine ethyl ester using the procedure described in Method 3 (400 mg, 62%). The title compound was prepared via hydrolysis of the ethyl ester using NaOH in ethanol. Proton and carbon NMR analyis indicated a mixture of diastereomers.

Provenance & Evidence