Ethanol → 1,4-Bis(ethoxycarbonyl)-2-(diphenylmethyl)-pyrrolidin-3-one

Participants

Reaction Steps

To a suspension of 80% sodium hydride (2.48 g, 83 mmol) in benzene (50 ml) was slowly added a solution of methyl 2- ethoxycarbonylamino- 3,3-diphenylpropanoate (Example 1b, 27.0 g, 83 mmol) in benzene (200 ml) and the mixture then heated at reflux for 1 h. Ethanol (1.0 ml) followed by ethyl acrylate (8.95 ml, 83 mmol) were added and the reaction heated at reflux for 2 h, the solvent was then distilled off and the residue allowed to cool to room temperature. A solution of the residue in water was added to a concentrated sulphuric acid/ice mixture and the product extracted into ethyl acetate. The organic phase was washed with saturated brine and dried (MgSO4). The residue was chromatographed on silica gel in dichloromethane/methanol (97:3) to give 1,4-bis(ethoxycarbonyl)-2-(diphenylmethyl)-pyrrolidin-3-one, m/z (CI+) 396(MH). A solution of this oil in 1.0M oxalic acid was heated at reflux for 8 h, cooled and the product extracted into chloroform. After separation the chloroform was removed in vacuo and the residue chromatographed on silica gel using ethyl acetate/hexane (1:4) as eluant to give 2-(diphenylmethyl)-1-ethoxycarbonylpyrrolidin-3 -one. 1H NMR (250 MHz, CDCl3) δ7.14-7.52 (10H, m), 4.80 (1H, br s), 4.68 (1H, vbr s), 4.18 (2H, br q), 3.94 (1H, vbs), 3.06 (1H, m), 2.34 (1H, m), 1.76 (1H, m), 1.22 (3H, t, J=7.0 Hz). m/z (CI+) 324(MH).

Provenance & Evidence