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Reagents and conditions: i) neat, 25 °C, 2 h ii) piperidine (cat), EtOH, reflux, 2 h iii) acid anhydride (for 3, 4, 5, 6 and 8) or isobutyl chloroformate (7), DMAP, pyridine, 0 to 25 °C, 2 h iv) trimethylacetic anhydride (9) or dimethylcarbamyl chloride (10), K2CO3, DMF, 25 °C, 18 h.
