Halogen - metal exchange of 3-substituted 1,2-dibromoarenes: the use of long-range JCH coupling constants to determine regiochemistry |
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Authors: | DiMichele Lisa Menzel Karsten Mills Paul Frantz Doug Nelson Todd |
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Institution: | Merck Research Laboratories, Department of Process Research, Merck & Co. Inc., Post Office 2000, Rahway, New Jersey 07065, USA. lisa_dimichele@merck.com |
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Abstract: | 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. |
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Keywords: | tri‐substituted arenes NMR 13C coupled 13C 1H 3JCH coupling constants 2JCH coupling constants regiochemistry HMBC |
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