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Diastereoselective synthesis of spiro[carbazole-3,5′-pyrimidines] and spiro[carbazole-3,1′-cyclohexanes] via four-component reaction†
Shao-Cong Zhan,Ren-Jie Fang,Jing Sun,Chao-Guo Yan
Organic & Biomolecular Chemistry Pub Date : 06/23/2021 00:00:00 , DOI:10.1039/D1OB01113H
Abstract

Functionalized spiro[carbazole-3,5′-pyrimidines] and spiro[carbazole-3,1′-cyclohexanes] were efficiently synthesized in satisfactory yields with high diastereoselectivity by CuSO4 catalyzed multicomponent reaction of indole-2-acetate, aromatic aldehyde and 1,3-dimethylbarbituric acid or dimedone. The reaction was finished with sequential Diels–Alder reaction of both in situ generated indole-2,3-quinodimethane and a dienophile. Additionally, the initially formed spiro[carbazole-3,5′-pyrimidines] were converted to dehydrogenated spiro[carbazole-3,5′-pyrimidines] by DDQ oxidation. The initially formed spiro[carbazole-3,1′-cyclohexanes] were converted to δ-valerolactone-substituted carbazoles by a DDQ promoted Baeyer–Villiger oxidation process.

Graphical abstract: Diastereoselective synthesis of spiro[carbazole-3,5′-pyrimidines] and spiro[carbazole-3,1′-cyclohexanes] via four-component reaction
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