The interrupted Fischer indole synthesis of arylhydrazines and biocatalytically generated chiral bicyclic imines selectively affords either tetracyclic pyrroloindolines or tricyclic tryptamine analogues depending on the reaction conditions. We demonstrate that the reaction is compatible with a variety of functional groups. The products are obtained in high optical purity and in reasonable to good yield. We present a plausible reaction mechanism to explain the observed reaction outcome depending on the stoichiometry of the acid mediator. To demonstrate the synthetic utility of our method, pharmaceutically relevant examples of both product classes were synthesized in highly efficient reaction sequences, including a phenserine analogue as a potential cholinesterase inhibitor and constrained tryptamine derivatives as selective inhibitors of the 5-HT₆ serotonin receptor and the TRPV1 ion channel.

The interrupted Fischer indole synthesis of arylhydrazines and biocatalytically generated chiral bicyclic imines selectively affords either tetracyclic pyrroloindolines or tricyclic tryptamine analogues depending on the reaction conditions. We demonstrate that the reaction is compatible with a variety of functional groups. The products are obtained in high optical purity and in reasonable to good yield. We present a plausible reaction mechanism to explain the observed reaction outcome depending on the stoichiometry of the acid mediator. To demonstrate the synthetic utility of our method, pharmaceutically relevant examples of both product classes were synthesized in highly efficient reaction sequences, including a phenserine analogue as a potential cholinesterase inhibitor and constrained tryptamine derivatives as selective inhibitors of the 5-HT₆ serotonin receptor and the TRPV1 ion channel.

Multiple applications of isothioureas as fine chemicals (or their precursors) are known, but a general sustainable method for their synthesis was hitherto unavailable. We report a novel general approach towards S-alkyl and S-aryl isothioureas through a copper(I)-catalyzed three-component reaction between amines, isocyanides, and thiosulfonates. The formal synthesis of a superpotent sweetener further illustrates the applicability of our method.

Isocyanides have been important building blocks in organic synthesis since the discovery of the Ugi reaction and related isocyanide-based multicomponent reactions. In the past decade isocyanides have found a new application as versatile C₁ building blocks in palladium catalysis. Palladium-catalyzed reactions involving isocyanide insertion offer a vast potential for the synthesis of nitrogen-containing fine chemicals. This Minireview discusses all the achievements in this emerging field.

Seit der Entdeckung der Ugi-Reaktion und ähnlicher Isocyanid- basierter Mehrkomponentenreaktionen sind Isocyanide wichtige Bausteine für die organische Synthese. In den letzten zehn Jahren fanden Isocyanide als vielseitige C₁-Bausteine in der Palladiumkatalyse eine neue Anwendung. Palladiumkatalysierte Reaktionen, die unter Isocyanidinsertion ablaufen, bieten ein enormes Potenzial für die Synthese stickstoffhaltiger Feinchemikalien. In diesem Kurzaufsatz werden alle erzielten Erfolge auf diesem neu entstehenden Gebiet diskutiert.

The combination of the recently developed multicomponent construction of highly substituted 3,4-dihydropyridones with subsequent allylation and intramolecular Heck-type cyclization allows the straightforward construction of benzo[a]quinolizines, a class of polycyclic compounds that – despite their interesting pharmacological and photochemical properties – have little precedent in the literature. After optimization of the individual steps, we used this reliable three-step sequence to generate a small library of diversely substituted benzo[a]quinolizines and various heterocyclic analogs.

The importance of palladium-catalyzed cross coupling reactions in contemporary organic synthesis is undisputed and underlined by the Nobel Prize for Chemistry in 2010. In addition to the highly efficient cross coupling reactions for single CC bond construction, palladium-catalyzed cascade processes involving multiple bond formations have emerged in recent years as valuable tools for the rapid synthesis of complex molecular scaffolds. This review presents an overview of the most relevant developments in this field, with a focus on the generation of diverse poly- and heterocyclic scaffolds. The generally well understood reactivity of palladium has allowed the discovery of many intriguing novel cascade processes, and the creativity of the synthetic community will undoubtedly lead to many more discoveries in the future.

Compared with the widespread use of carbonylative Pd-catalyzed cross-coupling reactions, similar reactions involving isocyanide insertion are almost virgin territory. We investigated the intramolecular imidoylative cross-coupling of N-(2-bromoaryl)amidines, leading to 4-aminoquinazolines. After thorough optimization of the reaction with respect to palladium source and loading, ligand, base, temperature, and solvent, a small library of 4-aminoquinazolines was prepared to determine the scope of this method. Various substituents are tolerated on the amidine and the isocyanide, providing efficient access to a broad range of diversely substituted 4-aminoquinazolines of significant pharmaceutical interest.