Cesium carbonate → Di-tert-butyl (4S)-N-(tert-butoxycarbonyl)-4-{4-[3-(tosyloxy)propoxy]benzyl}-L-glutamate

Participants

Reaction Steps

To 100 mg (0.22 mmol) of di-tert-butyl (4S)—N-(tert-butoxycarbonyl)-4-(4-hydroxy-benzyl)-L-glutamate (Example 1b) in 10 mL N,N-dimethylformamide were added 210 mg (0.64 mmol) of cesium carbonate and 413 mg (1.07 mmol) of 1,3-propanediol di-p-toluenesulfonate (Aldrich) and the resulting suspension was stirred overnight at room temperature. The reaction mixture was then filtered, the solvent evaporated and the residue was taken up in dichloromethane and 1 M hydrochloric acid. The organic phase was separated off, washed with water until neutral, dried over sodium sulfate and filtered, and the filtrate was concentrated in vacuo. The crude product obtained in this manner was chromatographed on silica gel using a hexane/ethyl acetate gradient, and the appropriate fractions were combined and concentrated.

Provenance & Evidence