General Methodology for the Preparation of Unsymmetrical α-Linked Bisenones via Ligandless Cross-Coupling Reactions

Ligand-free nickel catalyzed perfluoroalkylation of arenes and heteroarenes

We describe a "ligand-free" Ni-catalyzed perfluoroalkylation of heteroarenes to produce a diverse array of trfiluoromethyl, pentafluoroethyl and heptafluoropropyl adducts. Catalysis proceeds at room temperature via a radical pathway. The catalytic protocol is distinguished by its simplicity, and its wide scope demonstrates the potential in the late-stage functionalization of drug analogues and peptides.

Solvated Nickel Complexes as Stoichiometric and Catalytic Perfluoroalkylation Agents*

The acetonitrile-solvated [(MeCN)Ni(C₂ F₅ )₃ ]^- was prepared in order to compare and contrast its reactivity with the known [(MeCN)Ni(CF₃ )₃ ]^- towards organic electrophiles. Both [(MeCN)Ni(CF₃ )₃ ]^- and [(MeCN)Ni(C₂ F₅ )₃ ]^- successfully react with aryl iodonium and diazonium salts as well as alkynyl iodonium salts to give fluoroalkylated organic products. Electrochemical analysis of [(MeCN)Ni^II (C₂ F₅ )₃ ]^- suggests that, upon electro-oxidation to [(MeCN)_n Ni^III (C₂ F₅ )₃ ], reductive homolysis of a perfluoroethyl radical occurs, with the concomitant formation of [(MeCN)₂ Ni^II (C₂ F₅ )₂ ]. Catalytic C-H trifluoromethylations of electron-rich arenes were successfully achieved using either [(MeCN)Ni(CF₃ )₃ ]^- or the related [Ni(CF₃ )₄ ]^2- . Stoichiometric reactions of the solvated nickel complexes reveal that "ligandless" nickel is exceptionally capable of serving as reservoir of CF₃ groups under catalytically relevant conditions.

Total Synthesis of Chalaniline B: An Antibiotic Aminoxanthone from Vorinostat-Treated Fungus Chalara sp. 6661

Chalaniline B [1-anilino-2,8-dihydroxy-3-(hydroxymethyl)xanthone], an antibiotic previously isolated from vorinostat-treated Chalara sp., was prepared in 7 steps from 2-hydroxyxanthone by a route incorporating regioselective oxidative transformations (bromination at C1/C3, ketone directed Pd(II)-catalyzed hydroxylation at C8), installation of the C1-anilino moiety by a regioselective Buchwald-Hartwig amination reaction from 1,3-dibromo-2,8-dimethoxyxanthone, and late-stage hydroxymethylation at C3 using a Stille cross-coupling. Biological evaluation of deshydroxymethylchalaniline B (1-anilino-2,8-dihydroxyxanthone) revealed MIC values of 8 μg mL^-1 (25 μM) against both methicillin resistant S. aureus and B. subtilis.

Highly selective AlCl3 initiated intramolecular α-alkylation of α,β-unsaturated lactams and lactones

An unprecedented example of AlCl3 initiated intramolecular α-alkylation of α,β-unsaturated lactams and lactones is reported. A variety of substrates containing an intramolecular diene yield exclusively regioselective six-membered ring products. This reaction protocol generates a new stereo centre which may be of high interest for the functionalization of bioactive coumarin and quinolinone derivatives.