TMSOTf-Catalyzed [4 + 2] Annulation of Ynamides and β-(2-Aminophenyl)-α,β-ynones for the Synthesis 2-Aminoquinolines

Abstract

A metal-free TMSOTf-catalyzed [4 + 2] annulation of ynamides with β-(2-aminophenyl)-α,β-ynones enables the regiospecific and facile assembly of 2-aminoquinoline frameworks. The catalyst TMSOTf presented a remarkable advancement compared to previously reported transition-metal catalysts. A wide range of 3-aryl/alkyl-substituted 2-aminoquinolines were generated in moderate to excellent yields due to the mild conditions.2-Aminoquinoline and its derivatives represent a privileged structural motif in both natural products and biologically active pharmaceuticals owing to their multifarious pharmacological properties. 1,2 The simplest 2-aminoquinoline isolated from Leucopaxillus mushrooms possesses antibacterial, protease inhibitory, mutagenic, antitumor, and anthelmintic activities. 1 Synthetic 2-aminoquinolines also show various biological properties (Figure 1). 2 Owing to the wide utility of 2-