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.

Diastereo-divergent synthesis of saturated azaheterocycles has been achieved by tBuOK-mediated hydroamination of alkenyl hydrazones. DFT calculations suggested that the cation–π interactions between a potassium cation and aryl substituents on hydrazones give rise to 2,5-cis selectivity in pyrrolidines, which were synthesized by the reaction of γ,δ-unsaturated N-benzyl hydrazones. By contrast, 2,5-trans selectivity was observed when an isopropyl group was used as the substituent on hydrazones. An unusual 2,6-trans selectivity in piperidine formation was also realized using the present strategy.

The transformation of cyclic hemiacetals (lactols) into lactones has been achieved by Cu-catalyzed aerobic CC bond cleavage in the presence of N-hydroxy phthalimide (NHPI). The present process is composed of a multistep sequence including a) formation of exo-cyclic enol ethers by dehydration; b) addition of phthalimide N-oxyl radical to the enol ethers followed by trapping of the resulting C-radicals with molecular oxygen to form peroxy radicals; c) reductive generation of oxy radicals and subsequent β-radical fragmentation to generate lactones.

A method for the synthesis of amide-containing molecules was developed using vinyl azides as an enamine-type nucleophile towards carbon electrophiles, such as imines, aldehydes, and carbocations that were generated from alcohols in the presence of BF₃⋅OEt₂. After nucleophilic attack of the vinyl azide, a substituent of the resulting iminodiazonium ion intermediate migrates to form a nitrilium ion, which is hydrolyzed to afford the corresponding amide.

A method based on hydroamination mediated by inorganic base was developed for the synthesis of cyclic nitrones from alkenyl oximes. DFT calculations of the reaction pathway suggested that this hydroamination could proceed through an unprecedented nucleophilic amination of the unactivated alkene by the oxime nitrogen atom. The transition state of this reaction is stabilized by an ionic interaction between a metal cation such as K⁺ and the oxime oxygen and negatively charged alkene moiety.

Highly functionalized quinolines and pyridines could be synthesized by BF₃⋅OEt₂-mediated reactions of vinyl azides with N-aryl and N-alkenyl aldimines, respectively. The reaction mechanism could be characterized as formal [4+2]-annulation, including unprecedented enamine-type nucleophilic attack of vinyl azides to aldimines and subsequent nucleophilic cyclization onto the resulting iminodiazonium ion moieties.

A method for the synthesis of amide-containing molecules was developed using vinyl azides as an enamine-type nucleophile towards carbon electrophiles, such as imines, aldehydes, and carbocations that were generated from alcohols in the presence of BF₃⋅OEt₂. After nucleophilic attack of the vinyl azide, a substituent of the resulting iminodiazonium ion intermediate migrates to form a nitrilium ion, which is hydrolyzed to afford the corresponding amide.

A method based on hydroamination mediated by inorganic base was developed for the synthesis of cyclic nitrones from alkenyl oximes. DFT calculations of the reaction pathway suggested that this hydroamination could proceed through an unprecedented nucleophilic amination of the unactivated alkene by the oxime nitrogen atom. The transition state of this reaction is stabilized by an ionic interaction between a metal cation such as K⁺ and the oxime oxygen and negatively charged alkene moiety.

The fluorine-containing organic motif is becoming privileged in pharmaceuticals, agrochemicals, and functional materials, owing to its unique properties such as electron-withdrawing character, metabolic stability, and lipophilicity. Described herein is the PhI(OAc)₂-mediated radical trifluoromethylation of vinyl azides with Me₃SiCF₃ to efficiently generate α-trifluoromethyl azines. The resulting α-trifluoromethyl azines were successfully transformed to valuable fluorine-containing molecules such as α-trifluoromethyl ketones, β-trifluoromethyl amines, 5-fluoropyrazoles, and trifluoroethyl isoquinolines.

The fluorine-containing organic motif is becoming privileged in pharmaceuticals, agrochemicals, and functional materials, owing to its unique properties such as electron-withdrawing character, metabolic stability, and lipophilicity. Described herein is the PhI(OAc)₂-mediated radical trifluoromethylation of vinyl azides with Me₃SiCF₃ to efficiently generate α-trifluoromethyl azines. The resulting α-trifluoromethyl azines were successfully transformed to valuable fluorine-containing molecules such as α-trifluoromethyl ketones, β-trifluoromethyl amines, 5-fluoropyrazoles, and trifluoroethyl isoquinolines.

Efficient violet–blue-emitting molecules are especially useful for applications in full-color displays, solid-state lighting, as well as in two-photon absorption (TPA) excited frequency-upconverted violet–blue lasing. However, the reported violet–blue-emitting molecules generally possess small TPA cross sections. In this work, new 1,8-diazapyrenes derivatives 3 with blue two-photon-excited fluorescence emission were concisely synthesized by the coupling reaction of readily available 1,4-naphthoquinone O,O-diacetyl dioxime (1) with internal alkynes 2 under the [{RhCl₂Cp*}₂]–Cu(OAc)₂ (Cp*=pentamethylcyclopentadienyl ligand) bimetallic catalytic system. Elongation of the π-conjugated length of 1,8-diazapyrenes 3 led to the increase of TPA cross sections without the expense of a redshift of the emission wavelength, probably due to the rigid planar structure of chromophores. It is especially noteworthy that 2,3,6,7-tetra(4-bromophenyl)-1,8-diazapyrene (3c) has a larger TPA cross section than those of other molecules reported so far. These experimental results are explained in terms of the effects of extension of the π-conjugated system, intramolecular charge transfer, and reduced detuning energy.