General procedure for the synthesis of ethyl 4-methyl-4-piperidinecarboxylate hydrochloride from ethyl N-Boc-4-methyl-4-piperidinecarboxylate: a 1,4-dioxane solution (3 mL) of 4 M hydrogen chloride was slowly added to an ethanol solution (4 mL) of ethyl N-Boc-4-methyl-4-piperidinecarboxylate (0.34 g, 1.25 mmol). The reaction mixture was stirred at room temperature for 6 hours. After completion of the reaction, the solvent was removed by rotary evaporator and the residue obtained was treated with ether, filtered and washed with ether to afford ethyl 4-methyl-4-piperidinecarboxylate hydrochloride (0.3 g, 99% yield) as a white solid.LRMS (m/z): 172 (M + 1)+.
[1] Patent: WO2015/86693, 2015, A1. Location in patent: Page/Page column 121
[2] Patent: WO2015/86527, 2015, A1. Location in patent: Page/Page column 114
[3] Patent: WO2015/86525, 2015, A1. Location in patent: Page/Page column 117; 118
[4] Patent: WO2006/83003, 2006, A1. Location in patent: Page/Page column 37
[5] Patent: WO2006/59945, 2006, A1. Location in patent: Page/Page column 69