Scheme 2.
Preparation of quaternary salts 16–26. Reagents and conditions: (b) CH3I, EtOH, reflux, 24 h, 71%; (c) dibromoalkanes, DMF, 73 °C, 48 h, 33–94%.
Preparation of quaternary salts 16–26. Reagents and conditions: (b) CH3I, EtOH, reflux, 24 h, 71%; (c) dibromoalkanes, DMF, 73 °C, 48 h, 33–94%.