title: Rerouting nucleophilic substitution from the 4-position to the 2- or 6-position of 2,4-dihalopyridines and 2,4,6-trihalopyridines: the solution to a long-standing problem.
abstract: 2,4-Difluoro-, 2,4,6-trifluoro-, and 2,3,4,6-tetrafluoropyridine undergo nucleophilic substitution preferentially if not exclusively at the 4-position. However, after the introduction of a trialkylsilyl group at C-3 or C-5, the halogen at the 6-(2-)position is displaced selectively. This synthetically valuable regiocontrol can also be realized with other halopyridines such as 2,4-dichloro- and 2,4,6-trichloropyridine.
authors.affiliation: Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale, BCh, CH-1015 Lausanne, Switzerland. manfred.schlosser@epfl.ch
authors.forename: Manfred
authors.initials: M
authors.lastname: Schlosser
authors.forename: Thierry
authors.initials: T
authors.lastname: Rausis
authors.forename: Carla
authors.initials: C
authors.lastname: Bobbio