Hydrochloric Acid → 2-(3-t-Butyl-4-hydroxyphenyl)-1-(1,3,4-oxadiazol-2-yl)ethylcarbamic acid benzyl ester

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Reaction Steps

To a solution of Z-Tyr(3-tBu)-OMe (4.0 g, 10.39 mmol) in ethanol (100 ml), hydrazine monohydrate (6.4 ml, 103.9 mmol) was added at room temperature. The mixture was stirred overnight and evaporated under reduced pressure to remove the solvent. The thus obtained residue was mixed with ethyl orthoformate (100 ml) and p-toluenesulfonic acid monohydrate (198 mg, 1.04 mmol) at room temperature. The mixture was stirred for 1.5 hours and mixed with 1N HCl (100 ml). The mixture was stirred for 20 min., and extracted with ethyl acetate. The organic layer was washed with a saturated aqueous sodium bicarbonate solution and then with saturated brine, dried over anhydrous magnesium sulfate and evaporated to remove the solvent under reduced pressure; the thus obtained residue was subjected to silica gel column chromatography (developing solvent: ethyl acetate:n-hexane=1:1), giving the titled compound (1.34 g, 33%).

Provenance & Evidence