One-step hydroxylation of aryl and heteroaryl fluorides using mechanochemistry
Simple use of KOH allows the direct F to OH exchange of aromatic and heteroaromatic substrates under mechanochemical conditions. The reaction is performed in the absence of solvent with potassium hydroxide as OH source. As a result, this approach is both more atom economical and environmentally friendly than previously described methods for this transformation.
Braje, Wilfried,Geneste, Hervé,Rodrigo, Eduardo,Walter, Magnus W.,Wiechert, Rainer
supporting information
p. 1469 - 1473
(2022/03/07)
Concise Entries to 4-Halo-2-pyridones and 3-Bromo-4-halo-2-pyridones
Methods for the synthesis of both simple 4-halo-2-pyridones and more functionalized 3,4-di- and (3,4,5-tri)-halo-2-pyridones are described that are based on a combination of Sandmeyer and regioselective (copper-mediated) halogenation, with a 2-chloro or a 2-benzyloxy moiety serving as a masked 2-pyridone.
Honraedt, Aurélien,Gallagher, Timothy
supporting information
p. 67 - 69
(2015/12/26)
Lactam enolate-pyridone addition: Synthesis of 4-halocytisines
The application of a lactam enolate-pyridone addition sequence, originally developed for cytisine, has been applied successfully to generate the first examples of 4-halocytisines. Variation of the lactam component provides cyfusine and 4-fluorocyfusine.
Ortho-selectivity in SNAr substitutions of 2,4-dihaloaromatic compounds. Reactions with anionic nucleophiles
The nucleophilic addition of organic anions to aromatic compounds with halogens positioned both ortho and para to activating groups was studied in a variety of solvents. Substrates showed strong preferences for ortho substitution in most cases. Evidence is presented for activating group-dependent coordination, which contributes to very high ortho-selectivity in nonpolar solvents. This also drives the overall reaction rate in these solvents, and is of close to the same magnitude of rate increase derived from polar solvents. para-Products are maximized by using crown ethers in protic solvents. Solvent effects overall are very different from corresponding reactions with amine nucleophiles due primarily to the different charges present in the transition states, and to solvation of the nucleophile.