GHOSH, M. K.; ROUT, N.; GIRI, S.; RSC Adv. 6 (2016) 32, 26886-26894, http://dx.doi.org/10.1039/C6RA00036C ; Dep. Chem., Natl. Inst. Technol., Rourkela 769 008, Odisha, India; Eng.) -M. Tismer 30-043

Facile generation of quaternary carbon centres has been realised in the presence of phenyl trimethyl ammonium tribromide (PTAB) mediated oxidative dearomatisation.

This paper entails the first recognition of Phenyl Trimethyl Ammonium Tribromide (PTAB) as an effective reagent for spiro-cyclizations proceeding via oxidative dearomatization. The experiment exhibits economical, metal and ligand free one-pot accomplishment of these significant transformations. The described protocol presents the first generalised methodology of spiro-oxacycle synthesis which can be applied towards various directions. A stereoselective synthesis of oxa-spirocyclooxadieneones has been accomplished.

Transition‐metal‐free regioselecitive C−H arylation of 2‐naphthols with diaryliodonium salts has been developed. The reaction proceeds under very simple experimental conditions and affords a range of products with various substitution patterns. The method allows for the incorporation of electron‐deficient aryls, which complements well currently existing metal‐free aryl–aryl cross‐couplings of phenols that have been so far restricted to the introduction of electron‐rich aryl moieties. The mechanism of the reaction was studied by means of DFT calculations, demonstrating that the C−C bond formation occurs via a dearomatization of 2‐naphthol substrate, followed by a subsequent rearomatization by tautomerization. The computations show that the use of a low polarity solvent and an insoluble inorganic base is key to securing the high selectivity of the C−C coupling over a competing C−O arylation pathway, by preventing the incipient deprotonation of 2‐naphthol.

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