Copper-Catalyzed Electrophilic Amination of Heteroarenes via C–H Alumination

A highly efficient Cu-catalyzed electrophilic amination reaction of readily available heteroarenes with <i>O</i>-benzoyl hydroxylamines via a one-pot C–H alumination is reported. The reactions were catalyzed using 1 mol % of CuCl to afford various heteroaryl amines in good to excellent yields. The direct C–H lithiation/transalumination of heteroarenes and catalytic amination sequence can be performed in a single vessel on gram scales

Copper-Catalyzed Aza-Michael Addition of Aromatic Amines or Aromatic Aza-Heterocycles to α,β-Unsaturated Olefins

A highly efficient and mild Cu-catalyzed conjugate addition reaction of aromatic amines and aromatic aza-heterocycles to α,β-unsaturated olefins is described. The transformation is promoted by 3–7 mol % of a Cu complex generated in situ from a mixture of inexpensive CuCl, a readily available phosphine or imidazolium salt, and KO<i>t</i>-Bu at ambient temperature. A wide range of β-amino sulfone, β-amino nitrile, and β-amino carbonyl compounds is efficiently and selectively synthesized in high yields (62–99%)

Enhancement of Photoinduced Electron Transfer in Self-Assembled Polymer Films Using Mixed Metal–Terpyridine Complexes

The design and synthesis of photoactive polymeric systems are important in regard to solar energy harvesting and utilization. In this report, we synthesized photoactive polymeric thin films via iterative self-assembly using reversible metal–terpyridine (M–tpy) interactions. The growth rate of thin film deposition depends on the metal ion of choice. Ru­(II)­(tpy)₂-incorporated poly­(vinyl alcohol) also functionalized with tpy was subjected to iterative self-assembly on glass substrates. UV–vis spectroscopy and surface profilometer investigations show that the polymeric thin films with Cu­(II) grew 2 times faster than those with Zn­(II), attributed to the strong M–tpy interaction. Interestingly, photocurrent generated in the polymeric thin films with Zn­(II) was much higher than those of other films. The apparent diffusion rate constant (<i>k</i>_app) was measured for the electron hopping process via potential-step chronoamperometry. As a result, the <i>k</i>_app for the polymeric thin films with Zn­(II) was almost 2 times larger than those with other metal ions. The choice of metal ions appears crucial in the mixed metal–tpy complex systems not only for the film growth but also for the efficient photoinduced electron transfer

Copper-Catalyzed Aza-Michael Addition of 2‑Aminobenzoate to β‑Substituted α,β-Unsaturated Ketones: One-Pot Synthesis of 3‑Carbonyl-2-Substituted Quinolin-4(1<i>H</i>)‑ones

We present a new and straightforward one-pot process for the synthesis of 3-carbonyl-4-quinolone derivatives through highly efficient Cu-catalyzed aza-Michael addition of 2-aminobenzoates to β-substituted α,β-unsaturated ketones/cyclization/mild oxidation reactions. A broad range of new versatile 3-carbonyl-quinolin-4­(1<i>H</i>)-ones is prepared from readily available chemicals under mild reaction conditions with short reaction times, producing good to excellent yields (up to 99%)

Total Synthesis of Isohericerin, Isohericenone, and Erinacerin A: Development of a Copper-Catalyzed Methylboronation of Terminal Alkynes

Efficient and concise approaches for the synthesis of three bioactive natural products, isohericerin, isohericenone, and erinacerin A, are described in this paper. The key reactions employed include a Mannich reaction with commercially available hydroxy­benzoate and subsequent one-pot lactamization to afford the common precursor isoindolinone in 3 steps and a Suzuki–Miyaura coupling reaction to connect geranyl side chains to the isoindolinone core. In addition, the mild and efficient synthesis of the C5′-oxidized geranyl side unit of isohericenone is enabled by developing a highly regioselective and efficient method for the Cu-catalyzed methylboronation of functionalized terminal alkynes

Synthesis of α‑Borylmethyl‑(<i>E</i>)‑allylborons via Cu-Catalyzed Diboration of 1‑Substituted Allenols and Their Application in Stereoselective Aldehyde Allylation

1,2-Diborons with one boron atom each in the allyl and homoallyl positions are of great utility, especially as double-allylation reagents. However, only a few synthetic methods have been reported to date and have a limited substrate scope. Herein, we developed the Cu-catalyzed regio- and stereoselective synthesis of α-borylmethyl-(E)-allylborons from easily accessible 1-substituted allenols and bis(pinacolato)diboron. Importantly, this method allowed the highly efficient and regioselective formation of double-allylating diborons with diverse substituents, which would be otherwise cumbersome to synthesize, and could be successfully performed on a gram scale. The synthetic application of α-borylmethyl-(E)-allylborons was demonstrated by the enantio- and (Z)-selective allylation of aldehydes via Brønsted acid catalysis. Furthermore, (E)-allyl and (E)-homoallyl diols with excellent diastereoselectivity were generated by the Lewis acid catalyzed diastereo- and (E)-selective allyl transfer of (E)-allyldiborons to aldehydes. Using this strategy, the key intermediate in the construction of the C7–C12 fragment of (−)-discodermolide was also synthesized

<i>N</i>‑Heterocyclic Carbene-Based Conducting Polymer–Gold Nanoparticle Hybrids and Their Catalytic Application

Hybrid nanocomposites of <i>N</i>-heterocyclic carbene (NHC)-functionalized conducting polymers (CPs) with gold nanoparticles (AuNPs) were prepared by concurrent disproportionation and oxidative coupling. The formation of hybrid nanocomposites, NHC-CP/AuNPs, in the simultaneous process was confirmed by transmission electron microscopy, powder X-ray diffraction, cyclic voltammetry, and ¹³C solid-state NMR analyses. More importantly, the NHC group played a pivotal role in the dispersion of AuNPs. Further, NHC-CP/AuNPs exhibited good catalytic activity for the reduction of 4-nitrophenol

Torsionally Responsive Tropone-Fused Conjugated Polymers

Torsionally responsive molecular systems can change their electronic properties according to the dihedral angles and can be utilized as sensory materials. We have designed and synthesized novel tropone-fused conjugated polymers <b>PBTr</b>, <b>PBTr-T</b>, and <b>PBTr-Tz</b> that showed interesting dihedral-angle-dependent variations in UV–vis absorptions. Tropone-fused thiophene derivatives were prepared from one-step condensation of thiophene-3,4-dialdehyde and aliphatic ketones via a modular, facile, and high-yielding method. Subsequent halogenation and Stille cross-coupling polymerization with a bis­(stannyl)­benzo­dithiophene resulted in a tropone-fused conjugated polymer <b>PBTr</b>. We were also able to prepare thiophene- and thiazole-bridged polymers, <b>PBTr-T</b> and <b>PBTr-Tz</b>, respectively, using similar synthetic methods. Electronic absorptions of the newly synthesized <b>PBTrs</b> were measured in solutions and in films states. Substantial red-shifts occurred in the case of thiophene-bridged <b>PBTr-T</b>, whereas almost no shift was observed for thiazole-bridged <b>PBTr-Tz</b>. We attributed this to the substantial change in the torsional angle between the tropone-fused thiophene moiety and thiophene, which was further supported by density functional theory (DFT) calculations. Similar spectral changes of UV–vis absorptions were observed when a poor solvent (methanol) was introduced to a chloroform solution of <b>PBTr-T</b>. Reverse torsional angle variations were realized with initially planar <b>PBTr-Tz</b> by introducing steric hindrance through protonation on the thiazole rings. We believe that torsionally responsive tropone-fused conjugated polymers are promising as novel platforms for sensory applications