Potassium Carbonate → Di-tert-butyl (4R)-N-(tert-butoxycarbonyl)-4-[4-(2-fluoroethoxy)benzyl]-D-glutamate

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Reaction Conditions

Reaction Steps

To 93 mg (0.2 mmol) of di-tert-butyl (4R)—N-(tert-butoxycarbonyl)-4-(4-hydroxybenzyl)-D-glutamate in 4 mL N,N-dimethylformamide were added 56 mg (0.4 mmol) of powdered potassium carbonate and 69.6 mg (0.40 mmol) of 1-iodo-2-fluoroethane and the resulting suspension was heated for 1 h at 100° C. in a microwave oven. The reaction mixture was then filtered, the solvent evaporated and the residue was taken up in ethyl acetate and water. The organic phase was separated off, washed with water until neutral, dried over sodium sulfate and filtered, and the filtrate was concentrated in vacuo. Di-tert-butyl (4R)—N-(tert-butoxycarbonyl)-4-[4-(2-fluoroethoxy)benzyl]-D-glutamate was obtained as crude product (40 mg, 39.1%) and deprotected without further purification: 2 mL of trifluoro acetic acid were added to the oily residue and the solution was stirred for 2 d at room temperature. The excess of trifluoro acetic acid was evaporated and the residue was taken up three times in tetrahydrofuran and then evaporated. The resulting oil was chromatographed on C-18 reversed phase silica gel using a water/acetonitrile gradient, the appropriate fractions were combined and concentrated.

Provenance & Evidence