370 mg (0.81 mmol) of 3-ethyl 1-(4-nitrophenyl) 5-(4-ethylphenyl)piperidine-1,3-dicarboxylate, 245 mg (2.42 mmol) of 4-hydroxypiperidine and 112 mg (0.81 mmol) of potassium carbonate were added to 9 ml of DMF and heated in a single-mode microwave (Emrys Optimizer) at 150° C. for 15 min. For work-up, water was added and the reaction solution was extracted with ethyl acetate. The organic phase was dried with sodium sulphate and concentrated under reduced pressure. The residue was purified by preparative HPLC. Yield: 208 mg (66% of theory)
