Logistic flexibility in the preparation of isomeric halopyridinecarboxylic acids
Although there are many conceivable ways to functionalize, and specifically carboxylate, 2-chloro-4-(trifluoromethyl)pyridine optionally at all three vacant positions, it is more straightforward to prep. only 2-chloro-4-(trifluoromethyl)pyridine-3-carboxylic acid from this precursor and 6-chloro-4-(trifluoromethyl)pyridine-2- and -3-carboxylic acids from a different one, viz. 5-bromo-2-chloro-4-(trifluoromethyl)pyridine. In the same manner, it proved more convenient to convert 5-chloro-2-(trifluoromethyl)pyridine into only the 4- and 6-carboxylic acids and to make the 3-carboxylic acid from 3-bromo-5-chloro-2-(trifluoromethyl)pyridine. All model substrates for functionalization were readily accessible from the correspondingly substituted chloroiodopyridine through heavy halogen displacement by in situ generated (trifluoromethyl)copper. [on SciFinder (R)]
WOS:000225311400022
2004
60
51
11869
11874
CAN 142:113852
27-16
Heterocyclic Compounds (One Hetero Atom)
Ecole Polytechnique Federale,Institut de Chimie moleculaire et biologique,CHLausanne,Switz.
Journal
written in English.
40473-01-6 (2-Bromo-5-chloropyridine); 53939-30-3 (5-Bromo-2-chloropyridine); 73583-39-8 (3-Bromo-5-chloropyridine); 81290-20-2 (Trimethyl(trifluoromethyl)silane); 81565-18-6 (2-Chloro-4-trifluoromethylpyridine); 505084-58-2 Role: RCT (Reactant), RACT (Reactant or reagent) (prepn. of isomeric halopyridinecarboxylic acids); 39890-95-4P; 137628-17-2P (2,3-Dibromo-5-chloropyridine); 244221-57-6P (5-Chloro-2-iodopyridine); 401892-47-5P (5-Bromo-2-chloro-4-iodopyridine); 590371-81-6P; 823221-93-8P; 823221-94-9P; 823221-95-0P; 823221-96-1P; 823221-97-2P (3-Bromo-5-chloro-2-iodopyridine); 823222-22-6P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn. of isomeric halopyridinecarboxylic acids); 261635-77-2P; 749875-15-8P; 760147-01-1P; 823221-98-3P; 823222-00-0P; 823222-01-1P; 823222-02-2P; 823222-03-3P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of isomeric halopyridinecarboxylic acids)
REVIEWED
EPFL