Copper-catalyzed aerobic spirocyclization of biaryl-N-H-imines via 1,4-aminooxygenation of benzene rings

A synthetic method of azaspirocyclohexadienones has been developed through copper-catalyzed aerobic spirocyclization of biaryl-N-H-imines prepared by the reaction of biarylcarbonitriles and Grignard reagents.     

Understanding the Origins of Nucleophilic Hydride Reactivity of a Sodium Hydride–Iodide Composite

Sodium hydride (NaH) has been commonly used as a Brønsted base in chemical syntheses, while it has rarely been employed to add hydride (H^?) to unsaturated electrophiles. We previously developed a procedure to activate NaH through the addition of a soluble iodide source and found that the new NaH–NaI composite can effect even stereoselective nucleophilic hydride reductions of nitriles, imines, and carbonyl compounds. In this work, we report that mixing NaH with NaI or LiI in tetrahydrofuran (THF) as a solvent provides a new inorganic composite, which consists of NaI interspersed with activated NaH, as revealed by powder X‐ray diffraction, and both solid‐state NMR and X‐ray photoelectron spectroscopies. DFT calculations imply that this remarkably simple inorganic composite, which is comprised of NaH and NaI, gains nucleophilic hydridic character similar to covalent hydrides, resulting in unprecedented and unique hydride donor chemical reactivity.     

Hydride Reduction by a Sodium Hydride–Iodide Composite

Sodium hydride (NaH) is widely used as a Brønsted base in chemical synthesis and reacts with various Brønsted acids, whereas it rarely behaves as a reducing reagent through delivery of the hydride to polar π electrophiles. This study presents a series of reduction reactions of nitriles, amides, and imines as enabled by NaH in the presence of LiI or NaI. This remarkably simple protocol endows NaH with unprecedented and unique hydride‐donor chemical reactivity.     

Cyclization of (2‐Alkenylphenyl)carbonyl Compounds to Polycyclic Arenes Catalyzed by Copper(II) Trifluoromethanesulfonate or Trifluoromethanesulfuric Acid

Various polycyclic arenes, such as naphthalenes, tetrahydroantharacenes, tetrahydrotetracenes, dihydropentacenes, and dihydropentaphenes are prepared from 2‐alkenylphenyl ketones and aldehydes by the catalytic use of copper(II) trifluoromethanesulfonate (Cu(OTf)₂) or trifluoromethanesulfuric acid (TfOH).