Reductive CO2 Fixation via the Selective Formation of C–C Bonds: Bridging Enaminones and Synthesis of 1,4-Dihydropyridines

Herein, a selective tandem C–C bond-forming reaction with CO2 was developed to realize the bridging of enaminones and synthesis of 1,4-dihydropyridines, respectively. n-Butylamine significantly promoted this CO2 deoxymethylenation procedure catalyzed by 1,5,7-triazabicyclo[4.4.0]­dec-5-ene (TBD) and ZnCl2. The mechanism involving the formation of bis­(silyl)­acetal, nucleophilic addition, and amine elimination was also interpreted to clarify the bridging of two molecules of enaminones with CO2 and the generation of dihydropyridine derivatives.