[CH3:1][C:2]1([CH3:14])[CH2:7][C:6](=[O:8])[CH:5]([CH2:9][C:10](=O)[CH3:11])[C:4](=O)[CH2:3]1.C([O-])(=O)C.[NH4+:19].O>C(O)(=O)C>[CH3:11][C:10]1[NH:19][C:4]2[CH2:3][C:2]([CH3:14])([CH3:1])[CH2:7][C:6](=[O:8])[C:5]=2[CH:9]=1The crude tri-ketone from Example 37 was dissolved in 300 mL of acetic acid to which ammonium acetate (55 g, 0.714 mmol) was added. The reaction mixture was heated at 65° C. until all starting material had disappeared (2-3 h), cooled to RT, added to H2O, and washed with EtOAc. The organic layer was washed with saturated NaHCO3 (×3), brine (×1) and dried over MgSO4. Solvent was removed in vacuo and the oily residue was passed through a plug of silica. The appropriate fractions were collected and solvent was removed. The resulting solid was washed with EtOAc and hexanes (if too much hexanes is added the material crashing back out of solution after the addition of EtOAc will be gummy. To remedy this simply add a little EtOAc). The solid was filtered and washed with hexanes. More solid can be recovered by removing the solvent and repeating this procedure. LCMS m/z M+H=178.1. Approximately 5 g of a tan solid was collected and identified as 2,6,6-trimethyltetrahydroindol-4-one.
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