Facile Synthesis of 4-Oxo-4H-quinolizine-2-carboxamide Derivatives

Abstract

A facile synthetic method for the construction of 2-substituted-4-oxo-4H-quinolizine-based core structure has been successfully developed. The synthesis made use of a one-pot Stobbe condensation followed by cyclization starting from the commercially available 2-pyridinecarbaldehyde. The structure of the formed 4-oxo-4H-quinolizine-2-carboxylate was fully confirmed by mass spectra, ¹H NMR and ¹³C NMR, correlation spectrography, heteronuclear multiple bond correlation, and heteronuclear single quantum coherence (HSQC) spectra. The ethyl carboxylate moiety was then further functionalized via direct aminolysis by a range of amines to afford the corresponding 4-oxo-4H-quinolizine-2-carboxamides 4a–i in moderate to good yields.

GRAPHICAL ABSTRACT

Keywords:

• Carboxamide
• 4-oxo-4H-quinolizine
• Stobbe condensation

SUPPLEMENTAL MATERIAL

Full experimental detail, ¹H and ¹³C NMR spectra, IR, and MS data for this article can be accessed on the publisher’s website.