A palladium(II)-catalyzed arylation of a γ-C(sp)-H bond of protected amino acid is explored. The monoarylation is promoted by the commercially available, inexpensive phenanthroline ligand, and toxic silver salt is replaced by earth-abundant Mn(III)acetate. Subsequently, a hitherto unknown unsymmetrical diarylation at the γ-position is accomplished under the modified reaction conditions. Ligands have a prominent influence in both mono- and unsymmetrical diarylations.
An efficient and straightforward L-proline catalyzed one-pot synthesis of a series of biologically relevant gem-(b-dicarbonyl)arylmethanes has been developed via a three-component reaction between indoles, aldehydes and C-H activated acids by grinding them together under solvent-free conditions at room temperature. Mild reaction conditions, high atom-economy, good yields, and eco-friendliness are some of the salient features of the present protocol.
A simple, straightforward and highly efficient multicomponent one-pot synthesis of a series of pharmaceutically interesting benzopyranopyrimidine and 4H-chromene derivatives has been developed on the basis of low-cost and environment-friendly sodium formate catalyst via tandem reactions of salicylic aldehydes, malononitrile, and cyclic secondary amines in ethanol at room temperature. Nature of nucleophile used in this reaction directs the course of the reaction; cyclic secondary amines result in the formation of benzopyrano[2,3-d]pyrimidines, whereas thiophenol furnish corresponding 4-thio-subtituted 4H-chromenes under the same reaction conditions. High atom-economy, good yields, eco-friendly, and mild reaction conditions are some of the important features of this protocol.
A ruthenium(II)-catalyzed redox-neutral synthesis of dihydroisoquinoline-fused quinazolinone derivatives has been accomplished through the merger of C−H activation and alkene difunctionalization using quinazolinone as an inherent directing group. This intermolecular reaction proceeds rapidly and is complete within 10 min, providing the annulation product in high yields without any stoichiometric metal oxidant. Mechanistically, this tandem reaction proceeds through directed ortho C−H allylation followed by hydroamination with the proximal −CONH group, to furnish 6-methyl-5,6-dihydro-8Hisoquinolino[1,2-b]quinazolin-8-ones in a single operation. The carboxylic acid additive has a dual role in the formation of active catalyst and protodemetalation.
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