One-Pot Synthesis of N-Imidoyl-(1 H)-indoles via Palladium-Catalyzed Oxidative Insertion Domino Reaction with Isocyanide and Arylboronic Acid

One-Pot Synthesis of 2-Substituted Indoles and 7-Azaindoles via Sequential Alkynylation and Cyclization of 2-Iodo-N-mesylarylamines and Alkynes in the Presence of Cu2O

A one-pot process was developed to synthesize in moderate to high yield a series of 2-substituted indoles and 7-azaindoles starting from 2-iodo-N-mesylarylamines and terminal alkynes in the presence of Cu2O in DMF at 90-120 °C. Without isolation of any intermediate, our optimized conditions enabled the introduction of ester, phenyl, hydroxymethyl, hydroxyethyl, N-Boc-aminomethyl, and methyl at the 2-postion of indoles and 7-azaindoles. The reaction tolerates a variety of substrates containing halogens, or acid- or base-sensitive functional groups without requiring a Pd catalyst, a ligand, or a base.

Palladium-Catalyzed Tandem Cyclization of Functional Diarylalkynes and Isocyanides for the Assembly of Isochromeno[4,3-c]quinolines

A novel strategy for the synthesis of various isochromeno[4,3-c]quinolines via palladium-catalyzed tandem cyclization of functional diarylalkynes with isocyanides has been developed. This approach features excellent chemo- and regioselectivities as well as good functional group tolerance. Notably, 6-phenylimino-6H-isochromeno[4,3-c]quinolin-11-amines and 11-amino-6H-isochromeno[4,3-c]quinolin-6-ones can be selectively constructed by employing different protecting groups of functional diarylalkynes. The gram-scale and late-stage modifications further demonstrate the synthetic value of this method.

Recent Advances in Palladium-Catalyzed Isocyanide Insertions

Isocyanides have long been known as versatile chemical reagents in organic synthesis. Their ambivalent nature also allows them to function as a CO-substitute in palladium-catalyzed cross couplings. Over the past decades, isocyanides have emerged as practical and versatile C1 building blocks, whose inherent N-substitution allows for the rapid incorporation of nitrogeneous fragments in a wide variety of products. Recent developments in palladium catalyzed isocyanide insertion reactions have significantly expanded the scope and applicability of these imidoylative cross-couplings. This review highlights the advances made in this field over the past eight years.

Copper-Catalyzed Tandem Radical Cyclization of 8-Ethynyl-1-naphthyl-amines for the Synthesis of 2H-Benzo[e][1,2]thiazine 1,1-Dioxides and its Fluorescence Properties

A copper-catalyzed radical cascade dehydrogenative cyclization of N-tosyl-8-ethynyl-1-naphthylamines under air is described herein for the synthesis of thioazafluoranthenes. The reaction proceeds smoothly with high efficiency and a broad reaction scope. The product is indeed a new fluorophore and its photophysical properties are also investigated. Based on the results, we are pleased to find that the Stokes shift of amino-linked thioazafluoranthenes in dilute tetrahydrofuran is determined to be 143 nm (4830 cm^-1).

Humic acid as an efficient and reusable catalyst for one pot three-component green synthesis of 5-substituted 1H-tetrazoles in water

Humic acid is a non toxic, inexpensive, easily available high-molecular weight polymer. A simple and facile one pot three-component synthesis of 5-substituted 1H-tetrazoles from aldehydes, hydroxyamine hydrochloride and sodium azide using humic acid as an efficient catalyst in water is described. The method reported has several advantages such as high to excellent yields, easy work-up, mild reaction conditions, use of water as a green solvent, and a commercially available, nontoxic and reusable catalyst.

Palladium-catalyzed regioselective C–H alkynylation of indoles with haloalkynes: access to functionalized 7-alkynylindoles

A palladium-catalyzed exclusively selective alkynylation of indoles has been reported, affording concise access to 7-alkynylindoles from readily available starting materials.