反应详情

A flask containing a mixture of ethyl 2-diazo-3-oxo-3-phenylpropanoate (16C) (2.80 g, 12.84 mmol), 16B (4.45 g, 16.05 mmol) from previous step, and 128 mL of 1:1 toluene:dichloroethane was heated at 80° C. for about 10 minutes. A suspension of rhodium octanoate dimer (0.20 g, 0.26 mmol) in 25 mL toluene was added dropwise to the reaction mixture via an addition funnel. The reaction was held at 80° C. for an additional hour after the addition was completed. After the disappearance of 16C, the reaction was cooled to RT. Approximately 8 mL of TFA was then added and the reaction was allowed to stir overnight at RT. The reaction mixture was concentrated to a green oil then purified by flash chromatography on silica gel using 5% methanol/DCM to afford benzyl 3-(4-(ethoxycarbonyl)-2-oxo-5-phenyl-2,3-dihydro-1H-imidazol-1-yl)piperidine-1-carboxylate (16D) as a tan solid (2.50 g, 42%). 1H NMR (400 MHz, DMSO-d6) δ ppm 0.94 (t, J=7.07 Hz, 3H) 1.07-1.18 (m, 2H) 1.24 (br. s., 1H) 1.62-1.78 (m, 2H) 2.36-2.43 (m, 1H) 2.59-2.68 (m, 1H) 3.46-3.58 (m, 2H) 3.96 (q, J=6.91 Hz, 2H) 4.99 (s, 1H) 7.26-7.51 (m, 11H) 10.97 (s, 1H) ESI-MS: m/z 450.1 (M+H)+.

1. additionA flask containing
2. additionwas added dropwise to the reaction mixture via an addition funnel
3. waitThe reaction was held at 80° C. for an additional hour
4. additionafter the addition
5. concentrationThe reaction mixture was concentrated to a green oil
6. customthen purified by flash chromatography on silica gel using 5% methanol/DCM