An 'impossible' macrocyclisation using conformation directing protecting groups

A p-benzenetricarboxamide macrocycle linked through secondary cis amides is obtained via cyclisation and subsequent deprotection of a folded linear precursor. Secondary benzamides strongly prefer the trans conformation, therefore this synthesis can be considered 'impossible' without recourse to protecting groups. (C) 2009 Elsevier Ltd. All rights reserved.