One-Pot Synthesis of Dihydropyrans via CO2 Reduction and Domino Knoevenagel/oxa-Diels-Alder Reactions

Catalytic CO2 reduction with phenylsilane under solvent-free conditions was linked with the one-pot synthesis of 3,4-dihydropyrans from beta dicarbonyl compounds and styrenes. The synthesis includes three processes: (1) bis(silyl)acetal formation from CO2 and phenylsilane and a domino reaction of (2) Knoevenagel condensation and (3) inverse-electron-demand oxa-Diels-Alder reaction. The first process was catalyzed by a pentanuclear ZnII complex (0.07 mol %) to generate bis(silyl)acetals, which were hydrolyzed into formaldehyde to be used in the second step.

Automated summary

Catalytic CO2 reduction with phenylsilane under solvent-free conditions was utilized to synthesize 3,4-dihydropyrans from beta dicarbonyl compounds and styrenes in a one-pot reaction. The synthesis involves three steps: (1) formation of bis(silyl)acetal from CO2 and phenylsilane, followed by a domino reaction of (2) Knoevenagel condensation and (3) inverse-electron-demand oxa-Diels-Alder reaction. The first step is catalyzed by a pentanuclear ZnII complex (0.07 mol %) to generate bis(silyl)acetals, which are then hydrolyzed into formaldehyde for the second step.