Dimethyl Sulfoxide → 4-{3-Oxo-4-[2-(2,4,5-trifluoro-phenoxy)-ethyl]-3,4-dihydro-quinoxalin-2-yl}-piperazine-1-carboxylic acid tert-butyl ester

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Reaction Steps

t-BuOK (1.0 g, 8.9 mmol) was added to a mixture of 4-(3-oxo-3,4-dihydro-quinoxalin-2-yl)-piperazine-1-carboxylic acid tert-butyl ester (1 g, 9 mmol; from Step 2), THF (20 g) and DMSO (5 g) at room temperature. This mixture is added to a solution of 2-(2,4,5-trifluorophenoxy)ethyl methanesulfonate (2.45 g, 9.00 mmol; from Example 54, Step 4) in THF (20 g). After being stirred at room temperature overnight, water (100 g) and EtOAc (200 g) were added to the reaction mixture. The layers were separated and the organic layer was concentrated in vacuo. The residue was purified by chromatography on an MPLC-columnn using a continuous gradient (0-100% EtOAc in heptane) as eluent. Evaporation of solvent gave 0.5 g of the title compound as greasy crystals (not pure). 1H NMR analysis supports the stated structure. This material was used directly in the next step.

Provenance & Evidence