Halogen - metal exchange of 3-substituted 1,2-dibromoarenes: the use of long-range JCH coupling constants to determine regiochemistry.
Regioselective halogen/metal exchange reactions were carried out on a series of 3-substituted- 1,2-dibromoarenes. Product mixtures were quenched with CO2 to form the corresponding benzoic acid analogs to facilitate HPLC and NMR analysis. Substitution at the 3-position could readily be assigned on the basis of 2D HMBC long-range correlations, while assignment at the 2-position was not as straightforward. The use of three-bond J(CH) coupling constant measurements, extracted from 1-D 1H coupled 13C experiments, were necessary to render unequivocal regio assignments.
DiMichele
Lisa
L
Merck Research Laboratories, Department of Process Research, Merck & Co. Inc., Post Office 2000, Rahway, New Jersey 07065, USA. lisa_dimichele@merck.com
Menzel
Karsten
K
Mills
Paul
P
Frantz
Doug
D
Nelson
Todd
T
D001966:Bromine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry*; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry*
D008670:Metals; D010636:Phenols; D001966:Bromine