Palladium‐Catalyzed C2−H Arylation of Unprotected (N−H)‐Indoles “On Water” Using Primary Diamantyl Phosphine Oxides as a Class of Primary Phosphine Oxide Ligands

• Published in: ChemCatChem Vol. 10; no. 13; pp. 2915 - 2922
• Main Authors: Moncea, Oana, Poinsot, Didier, Fokin, Andrey A., Schreiner, Peter R., Hierso, Jean‐Cyrille
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 09.07.2018; Wiley Blackwell (John Wiley & Sons)
• Subjects: heterocycles; homogeneous catalysis; Indoles; ligand effects; Ligands; P ligands; Palladium; phosphanes; Phosphine oxide
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201800187

We present the Pd‐catalyzed arylation of (N−H)‐indoles with functionalized haloarenes “on water” using hitherto untested primary diamantyl phosphine oxides (PPO) as ligands. Remarkable C2−H arylation selectivity was achieved by employing functionalized iodoarenes and N‐unprotected indoles. We provide evidence that the in situ generated oxide of (9‐hydroxydiamant‐4‐yl)phosphine L1 is key for the reaction efficiency by comparing a set of diamantane‐based compounds structurally related to L1. Our results demonstrate the power of the new PPO ligands for the C−H functionalization of unprotected (N−H)‐heterocycles. Phosphine possibilities: (9‐Hydroxydiamant‐4‐yl)phosphine is key for the aerobic Pd‐catalyzed C2‐arylation of unprotected (N−H)‐indoles with functionalized haloarenes “on water”. Our results demonstrate the power of the new primary phosphine oxide ligands for the C−H functionalization of unprotected (N−H)‐heterocycles.