Synthesis
1-Boc piperidine-4-carbaldehyde (35.0 g, 164.1 mmol) was dissolved in dichloromethane (200 mL) and the solution was cooled to 0 °C. Potassium tert-butoxide (23.9 g, 213 mmol) was added to the solution with stirring, followed by slow addition of iodomethane (69.9 g, 492 mmol). The reaction mixture was stirred at 0 °C for 30 min, then gradually warmed to room temperature and continued stirring for 1.5 h. The reaction was completed by pouring the mixture into the solution. After completion of the reaction, the mixture was poured into brine (400 mL) and the organic layer was separated. The organic layer was dried with anhydrous sodium sulfate, filtered and concentrated. The crude product was purified by silica gel column chromatography to afford 1-Boc-4-formyl-4-methylpiperidine (16.36 g, 72.0 mmol, 43.8% yield).
References
[1] Patent: WO2008/118718, 2008, A2. Location in patent: Page/Page column 84
[2] Patent: WO2014/28384, 2014, A1. Location in patent: Page/Page column 112
[3] Patent: WO2014/164467, 2014, A1. Location in patent: Page/Page column 65
[4] Patent: WO2014/164428, 2014, A1. Location in patent: Page/Page column 61
[5] Patent: WO2013/127828, 2013, A1. Location in patent: Page/Page column 62
