Pot, atom and step economic (PASE) synthesis of 5-monoalkylbarbiturates through domino aldol-Michael reaction

Collective Syntheses of Guaiane Sesquiterpenes: Stereoselective Syntheses of (+)-Dysodensiol F, (+)-10β,14-Dihydroxy-allo-aromadendrane, and (-)-Dendroside C Aglycon

A collective synthetic route for tricyclic guaiane sesquiterpenes and total syntheses of (+)-dysodensiol F, (+)-10β,14-dihydroxy-allo-aromadendrane, and (-)-dendroside C aglycon starting from a versatile hydroazulene intermediate were accomplished. The key features of these syntheses involve late-stage carbene-mediated diastereoselective cyclopropanation, construction of an unusual cis-fused-hydroazulene skeleton via intramolecular Dieckmann condensation, and highly stereoselective tandem conjugate addition/intramolecular allylic alkylation to afford a 5/7/3 tricyclic skeleton of guaiane natural products. The synthesis of (-)-dendroside C aglycon and the first total synthesis of (+)-dysodensiol F and (+)-10β,14-dihydroxy-allo-aromadendrane are described in detail. Activation of the Nrf2/ARE signaling pathway by (-)-dendroside C aglycon is also disclosed via our synthesis.

Michael addition at neutral pH: a facile synthesis of 1,3-dinitroalkanes

Base-catalyzed Michael addition of nitroalkane to conjugated nitroalkene suffers serious practical difficulties due to the formation of oligomeric byproduct. Given its importance for synthesis of pharmacologically relevant organic compounds, a scalable synthesis of 1,3-dinitroalkane is developed by addition of nitroalkane to nitroalkene in aqueous phosphate buffer at pH 7.0 with no added traditional base catalyst.

Enantioselective organocatalytic Michael additions of N,N'-dialkylbarbituric acids to enones

N,N'-Dialkylbarbituric acids as cyclic malonamide donors were successfully used in the enantioselective Michael addition reaction of enones. Using cinchona alkaloid-based bifunctional squaramide as an organocatalyst, this Michael reaction of N,N'-di-tert-butylbarbituric acid with various enones features a highly enantioselective (91-99% ee) production of the corresponding optically active 5-substituted barbituric acid derivatives. The transformations of the Michael product for the barbituric acid structural unit were realized in two ways, deprotection to remove the N-tert-butyl group and alkylation to produce 5,5-disubstituted barbituric acid derivatives.

Organocatalytic domino Knöevenagel–Michael reaction in water for the regioselective synthesis of benzo[4,5]imidazo[1,2-a]pyrimidines and pyrido[2,3-d]pyrimidin-2-amines

An organocatalyzed aqueous media domino reaction is developed for the regioselective synthesis of benzo[4,5]imidazo[1,2-a]pyrimidines and pyrido[2,3-d]pyrimidin-2-amines.

Recent applications of barbituric acid in multicomponent reactions

This review aims to show representative examples of multicomponent reactions utilizing barbituric acid in the synthesis of various heterocyclic structures.