Cesium carbonate → [(6R,7S)-2-fluoro-6-methyl-8-oxo-9-(2,2,2-trifluoro-ethyl)-6,7,8,9-tetrahydro-5-oxa-9-aza-benzocyclohepten-7-yl]-carbamic acid tert-butyl ester

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Reaction Steps

A solution of 3.00 g (10.0 mmol) ((6R,7S)-2-fluoro-6-methyl-8-oxo-6,7,8,9-tetrahydro-5-oxa-9-aza-benzocyclohepten-7-yl)-carbamic acid tert-butyl ester and 3.37 g (15.0 mmol) 2,2,2-trifluoroethyl triflate in 30 ml dimethylformamide were treated with 4.73 g (15.0 mmol) cesium carbonate for 6 hours. The solvent was distilled off at low pressure and the residue was extracted with water/ethylacetate. Chromatography on silicagel with heptane/ethylacetate 100:0 to 0:100 yielded 3.79 g (99%) [(6R,7S)-2-fluoro-6-methyl-8-oxo-9-(2,2,2-trifluoro-ethyl)-6,7,8,9-tetrahydro-5-oxa-9-aza-benzocyclohepten-7-yl]-carbamic acid tert-butyl ester, MS m/e (%): 393.3 (M+H+, 100).

Provenance & Evidence