Dialkylterphenyl Phosphine‐Based Palladium Precatalysts for Efficient Aryl Amination of N‐Nucleophiles. Issue 5 (16th January 2020)

• Record Type: Journal Article
• Authors: Rama, Raquel J.; Maya, Celia; Nicasio, M. Carmen
• Is Part Of: Chemistry. Volume 26:Issue 5(2020)
• Page Start: 1064
• Page End: 1073
• Publication Date: 2020-01-16
• Subjects: aryl amination -- cross-coupling -- palladacycles -- phosphine complexes -- precatalysts; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201903279
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: A series of 2‐aminobiphenyl palladacycles supported by dialkylterphenyl phosphines, PR2 Ar′ (R=Me, Et, i Pr, Cyp (cyclopentyl), Ar′=Ar Dipp2, Ar Xyl2f, Dipp (2, 6‐C6H3‐(2, 6‐C6H3‐(CHMe2)2)2), Xyl=xylyl) have been prepared and structurally characterized. Neutral palladacycles were obtained with less bulky terphenyl phosphines (i.e., Me and Et substituents) whereas the largest phosphines provided cationic palladacycles in which the phosphines adopted a bidentate hemilabile k 1 ‐P, η 1 ‐Carene coordination mode. The influence of the ligand structure on the catalytic performance of these Pd precatalysts was evaluated in aryl amination reactions. Cationic complexes bearing the phosphines P i Pr2 Ar Xyl2 and PCyp2 Ar Xyl2 were the most active of the series. These precatalysts have demonstrated a high versatility and efficiency in the coupling of a variety of nitrogen nucleophiles, including secondary amines, alkyl amines, anilines, and indoles, with electronically deactivated and ortho ‐substituted aryl chlorides at low catalyst loadings (0.25–0.75 mol % Pd) and without excess ligand. Abstract : New ligands on the stage . Palladacycles bearing dialkylterphenyl phosphines mediated the arylation of a variety of N nucleophiles efficiently at low catalyst loadings and without excess ligand.