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

Kazuto Takaishi; Ritsuki Nishimura; Yuha Toda; Hajime Morishita; Tadashi Ema

doi:10.1021/acs.orglett.3c00047

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

Org Lett. 2023 Mar 10;25(9):1370-1374. doi: 10.1021/acs.orglett.3c00047. Epub 2023 Feb 24.

Authors

Kazuto Takaishi¹, Ritsuki Nishimura¹, Yuha Toda¹, Hajime Morishita¹, Tadashi Ema¹

Affiliation

¹ Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530, Japan.

PMID: 36826404
DOI: 10.1021/acs.orglett.3c00047

Abstract

Catalytic CO₂ reduction with phenylsilane under solvent-free conditions was linked with the one-pot synthesis of 3,4-dihydropyrans from β-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 Zn^II complex (0.07 mol %) to generate bis(silyl)acetals, which were hydrolyzed into formaldehyde to be used in the second step.