The geminal difluorocyclobutane core is a valuable structural element in medicinal chemistry. Strategies for gemdifluorocyclobutanes, especially the 2-substituted cases, are limiting and often suffer from harsh reaction conditions. Reported herein is a migratory gem-difluorination of aryl-substituted methylenecycloproanes (MCPs) for the synthesis of 2-arylsubstituted gemdifluorocyclobutanes. Commercially available Selectfluor (F-TEDA-BF 4 ) and Py•HF were used as the fluorine sources. The protocol proceeds via a Wagner−Meerwein rearrangement with mild reaction conditions, good functional group tolerance, and moderate to good yields. The product could be readily transformed to gem-difluorocyclobutane-containing carboxylic acid, amine, and alcohol, all of which are useful building blocks for biologically active molecule synthesis.Letter pubs.acs.org/OrgLett

A hypervalent iodine­(III)-mediated ring-contractive fluorination reaction of 2-alkylidenecyclobutanol derivatives is presented. The protocol allows the facile synthesis of β-monofluorinated cyclopropanecarbaldehydes via a fluorination/semipinacol rearrangement cascade using nucleophilic Py·HF as the fluorine source. For challenging electron-rich arene substrates, the installation of a protecting group on the free alcohol is pivotal for maintaining the reaction efficiency. The synthetic utility was demonstrated by the scalability of this reaction and further transformations of the products.

A direct conversion of a C(sp2)-F bond into the corresponding C(sp2)-C(sp3) bond using Al(alkyl)3 as the coupling partner under nickel catalysis is reported. Intriguingly, aryl fluorides, alkenyl monofluorides, and alkenyl...

Reported herein is an in situ-generated hypervalent iodine-incorporating fluoroarylation of benzylidenecyclopropanes using commercially available HF•Py and aryl iodides as fluorine and aryl sources, respectively. The reaction proceeds via regioselective 1,2-fluoroiodination of a double bond followed by an iodonio-[3,3]-rearrangement of the formed cyclopropyl-I (III) species. The protocol offers facile access to valuable monofluorinated 1,1-bisbenzyl-alkenes with mild reaction conditions and moderate to good yields. The synthetic utility of the products was demonstrated by further transformations. Preliminary mechanistic studies were conducted.