1,8-Diazabicyclo(5.4.0)undec-7-ene → HCID 19101692, compound

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Reaction Steps

5-Chloro-N-cyclopropyl-4-fluoro-2-nitroaniline (460 mg, 2 mmol) is heated to 80° for 40 hours with L-proline tert-butyl ester (342 mg, 2 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (304 mg, 2 mmol). The reaction mixture is then dissolved in a water/ethyl acetate mixture (1:1, 100 ml). The ethyl acetate phase is washed with 10 percent sodium chloride solution, dried over magnesium sulfate and evaporated under reduced pressure. The residue is chromatographed on silica gel (eluent: hexane/ethyl acetate 8:2). The product is crystallized from ether/n-hexane. There are obtained 94 mg (13%) of tert-butyl rac-1-[5-(cyclopropylamino)-2-fluoro-4-nitro-phenyl]pyrrole-2-carboxylate with a m.p. of 142°-143°.

Provenance & Evidence