Palladium‐Catalyzed Domino Synthesis of 2,3‐Difunctionalized Indoles via Migratory Insertion of Isocyanides in Batch and Continuous Flow

Transition-metal-free intramolecular double hydrofunctionalization of alkyne to access 6/7/5-fused heterocyclic skeletons

We describe a novel intramolecular double hydrofunctionalization cyclization of alkyne with nitrogen and oxygen nucleophilic groups to construct valuable 6/7/5-fused heterocyclic products. This post-Groebke-Blackburn-Bienaymé (GBB) reaction introduces a new class of functionalized isocyanides. Transition-metal-free cyclization, broad substrate scope, and high atom economy were some features of the present protocol.

Recent advances in Pd-catalyzed asymmetric cyclization reactions

Over the past few decades, there have been major developments in transition metal-catalyzed asymmetric cyclization reactions, enabling the convenient access to a wide spectrum of structurally diverse chiral carbo- and hetero-cycles, common skeletons found in fine chemicals, natural products, pharmaceuticals, agrochemicals, and materials. In particular, a plethora of enantioselective cyclization reactions have been promoted by chiral palladium catalysts owing to their outstanding features. This review aims to collect the latest advancements in enantioselective palladium-catalyzed cyclization reactions over the past eleven years, and it is organized into thirteen sections depending on the different types of transformations involved.

Palladium-Catalyzed Tandem C(sp3)-H Insertion Cyclization of 2-(2-Vinylarene)acetonitriles with Isocyanides to Access Naphthalen-2-amines

A Pd-catalyzed cyclization reaction of 2-(2-vinylarene)acetonitriles and isocyanides has been documented. Various naphthalen-2-amines were obtained in moderate to good yields under mild conditions. The in vitro cytotoxicity of all products was evaluated by MTT assay against seven human cancer cell lines. The results indicated that compounds 3ea, 3ma, and 3ob exhibited effective anticancer activities against the tested cancer cells.

Chemical insights into the synthetic chemistry of five-membered saturated heterocycles-a transition metal-catalyzed approach

Drug design and delivery is primarily based on the hunt for new potent drug candidates and novel synthetic techniques. Recently, saturated heterocycles have gained enormous attention in medicinal chemistry as evidenced by the medicinal drugs listed in the FDA Orange Book. Therefore, the demand for novel saturated heterocyclic syntheses has increased tremendously. Transition metal (TM)-catalyzed reactions have remained the prime priority in heterocyclic syntheses for the last three decades. Nowadays, TM catalysis is well adorned by combining it with other techniques such as bio- and/or enzyme-catalyzed reactions, organocatalysis, or using two different metals in a single catalysis. This review highlights the recent developments of the transition metal-catalyzed synthesis of five-membered saturated heterocycles.

Bicyclic Amidine-Triggered Cyclization of o-Alkynylisocyanobenzenes: Synthesis of Lactam-Derived Quinolines

Efficient access to the synthesis of lactam-derived quinoline through a bicyclic amidine-triggered cyclization reaction from readily prepared o-alkynylisocyanobenzenes has been developed. The reaction was initiated by nucleophilic attack of the bicyclic amidines to o-alkynylisocyanobenzenes, subsequently with intramolecular cyclization to produce a DBU-quinoline-based amidinium salt, followed by hydrolysis to afford the lactam-derived quinoline in moderate to good yields.

Synthesis of Azepinoindoles via Pd-Catalyzed C(sp2)-H Imidoylative Cyclization Reactions

An efficient and convenient method for the construction of diverse free (N-H)-benzazepinoindoles by Pd-catalyzed C(sp²)-H imidoylative cyclization of 3-(2-isocyanobenzyl)-1H-indoles was developed. The reaction shows a wide substrate scope and can be scaled up, providing a practical route to valuable bioactive azepinoindoles.

Advances in palladium-catalysed imidoylative cyclization of functionalized isocyanides for the construction of N-heterocycles

Palladium-catalysed isocyanide insertion reactions have witnessed great progress in recent years. In particular, imidoylative cyclization of functionalized isocyanides was successfully developed by taking advantage of the adjustable substituents on the isocyano group, opening a new avenue to access a variety of nitrogen-containing heterocycles. In this review article, we summarize the advances of functionalized isocyanide insertion reactions and highlight the breakthroughs of enantioselective palladium catalysed imidoylation reactions by using this strategy. Additionally, copper-catalysed cyclization reactions of functionalized isocyanides are briefly discussed.