Synthesis of dinuclear palladium complexes having two parallel isocyanide ligands, and their application as catalysts to pyrrole formation from tert-butylisocyanide and alkynes

Abstract

a b s t r a c tNovel dinuclear palladium complexes having two isocyanide ligands were synthesized by using a binucleating ligand, N,N 0 -bis[2-(diphenylphsphino)phenyl]formamidinate (dpfam). The structure of [Pd 2 (l-dpfam)(tert-BuNC) 2 ]Cl was confirmed by X-ray analysis, showing that the Pd-Pd bond length of 2.5824(3) Å falls well within the range of those for known dipalladium complexes having the edge-sharing structure and two isocyanides coordinate to palladium in almost parallel and in close proximity. The dinuclear complex [Pd 2 (l-dpfam)(tert-BuNC) 2 ]PF 6 served as catalyst for pyrrole formation from tertbutylisocyanide and various alkynes.

DFT Study on Dinuclear Palladium Complex Catalyzed Pyrrole Formation From tert‐Butyl Isocyanide and Alkynes

“…The corresponding bond lengths in original experiments are 2.58, 2.06 and 2.06 Å, respectively. [39] The additional calculations show that the level of theory we used is reliable for the systems studied in this work.…”

“…However, when the mononuclear palladium complex Pd(PPh 3 ) 4 was used as the catalyst, the yield of product pyrroles decreased. [39] In this work, we proposed a reaction mechanism to account for the dinuclear palladium complex catalyzed pyrrole formation. A detailed DFT study was carried out aimed at obtaining deeper insight into the mechanism of the present pyrrole formation from tert-butylisocyanide and alkynes.…”

Transition Metal-Mediated Synthesis of Monocyclic Aromatic Heterocycles

“…A subsequent reductive elimination would give 3-561e producing pyrrole upon tautomerization 3-562 . 477 …”

Palladiumkatalysierte migratorische Insertion von Isocyaniden: eine neue Methode für die Kreuzkupplungschemie

“…[50] Die Reaktion umfasst die Insertion von drei Isocyaniden sowie die Abspaltung von 2-Methyl-1-propen und wurde nur mit tert-Butylisocyanid (2) durchgeführt. [50] Die Reaktion umfasst die Insertion von drei Isocyaniden sowie die Abspaltung von 2-Methyl-1-propen und wurde nur mit tert-Butylisocyanid (2) durchgeführt.…”

“…[47] Die bençtigten 9-Alkyl-BBN-Derivate (119) wurden in situ hergestellt und direkt eingesetzt. Die Reaktion hängt stark vom stçchiometrischen Verhältnis zwischen tert-Butylisocyanid (2) und der 9-BBN-Spezies (119) [50] Die Reaktion umfasst die Insertion von drei Isocyaniden sowie die Abspaltung von 2-Methyl-1-propen und wurde nur mit tert-Butylisocyanid (2) durchgeführt.…”