4-Chlorophenyl Isocyanate → (3S)-2N-(4-chlorophenylaminocarbonyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid

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Reaction Steps

To a solution of (S) 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (1.00 g, 2.44 mmol) in 1N aq. NaOH (10 mL), a solution of 4-chlorophenylisocyanate (563 mg, 3.66 mmol) in dioxane (8 mL) was added. The mixture was stirred at room temperature overnight. More 4-chlorophenylisocyanate (600 mg, 3.91 mmol) in dioxane (5 mL) was added. It was stirred for another day. It was then washed with Et2O (2×). The aqueous layer was separated, acidified with 4N HCl to pH 1 to 2. The product was extracted with EtOAc. The EtOAc solution was dried over Na2SO4, concentrated in vacuo to give a solid (1.50 g), which was sufficiently pure to be used in the next reaction. MS 391.1 and 393.1 (M+H, Cl pattern).

Provenance & Evidence