TY - JOUR
T1 - Palladium catalyzed C-H functionalization of O-arylcarbamates
T2 - Selective ortho -bromination using NBS
AU - John, Alex
AU - Nicholas, Kenneth M.
PY - 2012/7/6
Y1 - 2012/7/6
N2 - 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).
AB - 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).
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U2 - 10.1021/jo300713h
DO - 10.1021/jo300713h
M3 - Article
C2 - 22663545
AN - SCOPUS:84863612454
SN - 0022-3263
VL - 77
SP - 5600
EP - 5605
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 13
ER -