Palladium-catalyzed cross-coupling reaction of azides with isocyanides

Abstract

An efficient palladium-catalyzed cross-coupling reaction of azides with isocyanides is developed, providing a general synthetic route to unsymmetric carbodiimides with excellent yields. This method shows a broad substrate scope, including not only aryl azides, but also unactivated benzyl and alkyl azides. Furthermore, from readily available substrates, Pd-catalyzed coupling with a tandem amine insertion cascade to obtain unsymmetric trisubstituted guanidines has been achieved in a one-pot fashion.

Transition‐Metal‐Catalyzed Cross‐Coupling and Sequential Reactions of Azides with Isocyanides

“…When 1‐azido‐2‐bromobenzene was treated with isocyanide and piperidine under the dual catalysis of Pd‐ and Cu‐ catalysts, an imidazole derivative was obtained in a total yield of 72% (Scheme 22). [17] …”

Efficient Synthesis of 4H-3,1-Benzoxazine Derivatives via One-Pot Sequential Passerini-Azide/Palladium-Catalyzed Azide–Isocyanide Coupling/Cyclization Reaction

“…18 In 2015, Zhang and co-workers reported a study on the crosscoupling reaction of azides and isocyanides with palladium as catalyst to generate carbodiimides (Scheme 1a). 19 In 2019, Ji and co-workers developed a Pd-catalyzed multicomponent reaction of sulfonyl azides, primary amines and methyl -isocyanoacetates for the synthesis of polysubstituted imidazolones (Scheme 1b). 20 However, as far as we know, there is no report on the sequential IMCR/azide-isocyanide coupling reaction for the synthesis of heterocycles.…”

Heterogeneous photocatalysis of azides: extending nitrene photochemistry to longer wavelengths

“…3,6,14 Palladium species are also known as promoters for N2 extrusion from azides. 15 We have previously shown that the use of metal-decorated TiO2 as photocatalyst can facilitate transfer hydrogenation reactions using the solvent as H source. 16,17 Particularly, it has been suggested that Pd-H species are prone to be generated in materials such as Pd-decorated TiO2 (Pd@TiO2) under illumination.…”

“…Concomitantly, azides can undergo N2 extrusion (plausibly assisted by -Pd interactions in the cases of aromatic azides) to produce nitrenes that can be stabilized on the Pd surface in a manner similar to the documented interaction of nitrogen centred species with PdNP 23 and Pd complexes. 15 At this point, with N2 gone, the fate of the nitrenes will be determined by their interactions with available hydrogen atoms or other organic materials that can populate the Pd surface. The discussion that follows centres on selected examples from the scope of the reaction that is presented later in this contribution.…”