Alkali Metal Amide-Catalyzed α-Deuteration of Sulfides.

The catalytic α-deuteration of sulfides was developed under mild conditions by using alkali metal amides [KN(SiMe) and CsN(SiMe)] as the catalyst. This approach successfully achieves a selective and efficient H/D exchange reaction of sulfides with D without using transition metal catalysts. A series of deuterium-labeled thioanisoles and alkyl methyl sulfides were obtained in good to high levels of deuterium incorporation.

Distance-Triggered Distinct Aryl Migrations on Azidodiboranes.

Derived from structurally similar precursors, two different azidodiboranes went through distinct aryl migration reactions triggered by different boron-boron separation distances. Biphenylene based diborane with a shorter boron-boron distance underwent heterolateral aryl migration to form a seven-membered azadiborepin, while xanthrene based diborane with a longer boron-boron distance afforded a stable bis-azidoborane scaffold. The pyrolysis of such a bis-azidoborane led to eight-membered oxazadiborocine through homolateral aryl migration and subsequent [3+2] cycloaddition.

Cesium Amide-Catalyzed Selective Deuteration of Benzylic C-H Bonds with D and Application for Tritiation of Pharmaceuticals.

Hydrogen isotope exchange (HIE) represents one of the most attractive labeling methods to synthesize deuterium- and tritium-labeled compounds. Catalytic HIE methods that enable site-selective C-H bond activation and exchange labeling with gaseous isotopes D and T are of vital importance, in particular for high-specific-activity tritiation of pharmaceuticals. As part of our interest in exploring s-block metals for catalytic transformations, we found CsN(SiMe ) to be an efficient catalyst for selective HIE of benzylic C-H bonds with D gas.

Neutral Boryl Radicals in Mixed-Valent B Br-B Adducts.

The general strategies to stabilize a boryl radical involve single electron delocalization by π-system and the steric hinderance from bulky groups. Herein, a new class of boryl radicals is reported, with intramolecular mixed-valent B Br-B adducts ligated by a cyclic (alkyl)(amino)carbene (CAAC). The radicals feature a large spin density on the boron center, which is ascertained by EPR spectroscopy and DFT calculations.

Nitrogen fixation and transformation with main group elements.

Nitrogen fixation is essential for the maintenance of life and development of society, however, the large bond dissociation energy and nonpolarity of the triple bond constitute a considerable challenge. The transition metals, by virtue of their combination of empty and occupied d orbitals, are prevalent in the nitrogen fixation studies and are continuing to receive a significant focus. The main group metals have always been considered incapable in dinitrogen activation owing to the absence of energetically and symmetrically accessible orbitals.

Direct alkylation of N,N-dialkyl benzamides with methyl sulfides under transition metal-free conditions.

Amides are a fundamental and widespread functional group, and are usually considered as poor electrophiles owing to resonance stabilization of the amide bond. Various approaches have been developed to address challenges in amide transformations. Nonetheless, most methods use activated amides, organometallic reagents or transition metal catalysts.

Alkyl lithium-catalyzed benzylic C-H bond addition of alkyl pyridines to α-alkenes.

Brønsted base catalyzed C-C bond formation reactions have been extensively utilized as reliable, efficient, and atom economical methods in organic synthesis. However, the electrophiles were mostly limited to polar ones such as imines, carbonyl compounds, α,β-unsaturated compounds, styrenes and conjugated dienes. The use of α-alkenes as electrophiles in the C-C bond formation reactions always needs transition metal catalysts.

Dimeric Potassium Amide-Catalyzed α-Alkylation of Benzyl Sulfides and 1,3-Dithianes.

The first catalytic α-alkylation reaction of benzyl sulfides and 1,3-dithianes with styrenes and conjugated dienes was developed under mild conditions by using a readily available Brønsted base potassium bis(trimethylsilyl)amide (KHMDS) as catalyst. The reaction displayed good functional group tolerance, high efficiency, and excellent chemoselectivity. A series of desired alkylation products were obtained in good to high yield.

Lithium Diisopropylamide Catalyzed Allylic C-H Bond Alkylation with Styrenes.

Allylic substitution reactions, a well-established approach for new bond construction, often need transition-metal catalysts and stoichiometric amounts of organometallic reagents, strong bases, or oxidants. Lithium diisopropylamide (LDA), a widely used and commercially available Brønsted base, is herein reported to catalyze the allylic C-H bond addition of 1,3-diarylpropenes to styrenes. Preliminary mechanism studies have provided a solid structure of the π-allyllithium intermediate and revealed the unique catalytic roles of LDA and its conjugate acid diisopropylamine.

Potassium-Zincate-Catalyzed Benzylic C-H Bond Addition of Diarylmethanes to Styrenes.

Direct functionalization of the benzylic C-H bond of diarylmethanes is an important strategy for the synthesis of diarylmethine-containing compounds. However, the methods developed to date for this purpose require a stoichiometric amount (usually more) of either a strong base or an oxidant. Reported here is the first catalytic benzylic C-H bond addition of diarylmethanes to styrenes and conjugated dienes.

Potassium Amide-Catalyzed Benzylic C-H Bond Addition of Alkylpyridines to Styrenes.

The benzylic functionalization of alkylpyridines is an important pathway for pyridine derivatives synthesis. The reaction partners, however, were mostly limited to highly reactive polar electrophiles. Herein, we report a potassium amide-catalyzed selective benzylic C-H bond addition of alkylpyridines to styrenes.

Nickel-catalyzed C-N bond reduction of aromatic and benzylic quaternary ammonium triflates.

A nickel-catalyzed, efficient C-N bond reduction of aromatic and benzylic ammonium triflates has been developed using sodium isopropoxide as a reducing agent. The high efficiency, mild conditions, and good compatibility with various substituents made this method an effective supplement to the current catalytic hydrogenation reactions. Combining this reductive deamination reaction with directed aromatic functionalization reactions, a powerful strategy for regioselective functionalization of arenes was demonstrated using dialkylamine groups as traceless directing groups.

The copper-catalyzed aerobic oxidative amidation of tertiary amines.

A general and efficient method for the synthesis of tertiary amides has been developed via the copper-catalyzed aerobic oxidative amidation of tertiary amines. Due to the use of the O2 oxidant, various functional groups were well tolerated under the present conditions. Extensive substrates studies demonstrated its potential as a practical approach for the synthesis of tertiary amides.

Palladium-Catalyzed Oxidative Arylation of Tertiary Benzamides: Para-Selectivity of Monosubstituted Arenes.

A mild and efficient protocol for the high para-selective arylation of monosubstituted arenes with tertiary benzamides has been developed via palladium-catalyzed oxidative coupling reactions. Due to the mild conditions and the easy availability of substrates and oxidant, this method could potentially provide a practical approach for the synthesis of para-substituted biaryl compounds.

A conceptual translation of homogeneous catalysis into heterogeneous catalysis: homogeneous-like heterogeneous gold nanoparticle catalyst induced by ceria supporter.

Translation of homogeneous catalysis into heterogeneous catalysis is a promising solution to green and sustainable development in chemical industry. For this purpose, noble metal nanoparticles represent a new frontier in catalytic transformations. Many challenges remain for researchers to transform noble metal nanoparticles of heterogeneous catalytic active sites into ionic species of homogeneous catalytic active sites.

Rare-earth-catalyzed C-H bond addition of pyridines to olefins.

An efficient and general protocol for the ortho-alkylation of pyridines via C-H addition to olefins has been developed, using cationic half-sandwich rare-earth catalysts, which provides an atom-economical method for the synthesis of alkylated pyridine derivatives. A wide range of pyridine and olefin substrates including α-olefins, styrenes, and conjugated dienes are compatible with the catalysts.

Nickel-catalyzed efficient and practical Suzuki-Miyaura coupling of alkenyl and aryl carbamates with aryl boroxines.

Suzuki-Miyaura coupling of unactivated alkenyl carbamates is described to construct polysubstituted olefins. The developed process is also suitable for heteroaromatic and even electron-rich aromatic carbamates.

Biaryl construction through Kumada coupling with diaryl sulfates as one-by-one electrophiles under mild conditions.

Diaryl sulfates were successfully applied as one-by-one organo electrophiles in Kumada coupling to construct biaryls with the emission of harmless inorganic salts.

Cross-coupling of alkenyl/aryl carboxylates with Grignard reagent via Fe-catalyzed C-O bond activation.

Iron-catalyzed cross-coupling of alkenyl/aryl carboxylates with primary alkyl Grignard reagent was described. This reaction brought a new family of electrophiles to iron catalysis. The combination of an inexpensive carboxylate electrophile and an iron catalyst would generate ample advantages.

Carbon-carbon formation via Ni-catalyzed Suzuki-Miyaura coupling through C-CN bond cleavage of aryl nitrile.

The Suzuki-Miyaura coupling of aryl nitriles with aryl/alkenyl boronic esters is reported. With this method, the cyano group could be applied as a protecting group of arenes and finally as a leaving group to further construct polyaryl scaffolds.

Biaryl construction via Ni-catalyzed C-O activation of phenolic carboxylates.

Biaryl scaffolds were constructed via Ni-catalyzed aryl C-O activation by avoiding cleavage of the more reactive acyl C-O bond of aryl carboxylates. Now aryl esters, in general, can be successfully employed in cross-coupling reactions for the first time. The substrate scope and synthetic utility of the chemistry were demonstrated by the syntheses of more than 40 biaryls and by constructing complex organic molecules.