Palladium-catalyzed carbonylative coupling of pyridine halides with aryl boronic acids |
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Authors: | Samuel Couve-BonnaireJean-François Carpentier André MortreuxYves Castanet |
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Institution: | a Laboratoire de Catalyse de Lille, UMR 8010 CNRS-Université de Lille 1, Ecole Nationale Supérieure de Chimie de Lille, BP 108, 59652 Villeneuve d'Ascq Cedex, France b Organométalliques et Catalyse, Institut de Chimie, UMR 6509 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France |
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Abstract: | The carbonylative Suzuki cross-coupling of a variety of mono-iodopyridines and bromopyridines (1a,b, 3a-c, 5) catalyzed by palladium-phosphane systems has been studied to prepare benzoylpyridine derivatives (2, 4, 6). The selectivity and the rate of the reaction are highly dependent on the reaction conditions, i.e. nature of the palladium catalyst precursor, solvent, temperature and CO pressure. The main side-products arise from direct, non-carbonylative cross-coupling. Under optimized conditions, benzoylpyridines are recovered in high yields (80-95%). The order of reactivity decreases from iodo- to bromopyridines and from 2-, 4- to 3-substituted halopyridines. The reactivity of dihalopyridines has been investigated; 2,6-dibromopyridine (7) and 3,5-dibromopyridine (11) are selectively transformed into either the corresponding benzoyl-phenylpyridine (8, 12) or the corresponding dibenzoylpyridine (9, 13). Dissymmetric 2,5-dihalopyridines (15a,b) are transformed into 2-benzoyl-5-bromopyridine (16) or 2,5-dibenzoylpyridine (17) in high yields. |
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Keywords: | carbonylation cross-coupling ketones palladium pyridines |
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