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

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 delta-valerolactone-substituted carbazoles by a DDQ promoted Baeyer-Villiger oxidation process.

Automated summary

Functionalized spiro[carbazole-3,5 '-pyrimidines] and spiro[carbazole-3,1 '-cyclohexanes] were efficiently synthesized in satisfactory yields with high diastereoselectivity using CuSO4-catalyzed multicomponent reactions. The initial compounds were further converted to new compounds using different oxidation methods.