Palladium catalyzed C-H functionalization of O-arylcarbamates: Selective ortho -bromination using NBS

Alex John, Kenneth M. Nicholas

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59 Scopus citations

Abstract

A series of cyclometalated palladium complexes derived from O-phenylcarbamates has been synthesized by the reaction of the respective carbamates with Pd(OAc) 2 in the presence of acids, CF 3CO 2H, CF 3SO 3H, and p-TsOH. The palladacycles were observed to coordinate amines and electron rich anilines but not sulfonamides or carboxamides. Analysis of the tBu-NH 2 adduct of the palladacycle 2b (2b• tBu-NH 2) by NMR spectroscopy (NOE) revealed a cis-coordination of the amine. However, the amine adducts failed to undergo ortho-amination (C-N bond formation) under varied reaction conditions. Notably, the palladacycle 1d was found to react efficiently with N-iodosuccinimide (NIS) to yield the ortho-iodinated carbamate, 1e. More significantly, this reaction can be extended to a palladium-catalyzed ortho C-H bromination of aryl-O-carbamates even at 5 mol % loading of Pd(OAc) 2 using N-bromosuccinimide (NBS).

Original languageEnglish (US)
Pages (from-to)5600-5605
Number of pages6
JournalJournal of Organic Chemistry
Volume77
Issue number13
DOIs
StatePublished - Jul 6 2012

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