Additive-free coupling of bromoalkynes with secondary phosphine oxides to generate alkynylphosphine oxides in acetic anhydride.

A coupling of bromoalkynes with secondary phosphine oxides was developed for the synthesis of alkynylphosphine oxides. This transformation was accomplished under additive-free conditions in acetic anhydride (Ac2O). The reaction could be carried out under mild conditions, and a wide range of secondary phosphine oxides were obtained in good yields.

Visible-Light-Initiated Na2-Eosin Y Catalyzed Highly Regio- and Stereoselective Difunctionalization of Alkynes with Alkyl Bromides.

A highly regioselective and stereoselective addition of alkyl bromides (amino-brominated aromatic ß,ß-dicyanoalkenes) to arylacetylenes by photoredox catalysis was developed. This difunctionalization of arylacetylenes was accomplished under ambient and metal-free conditions to produce alkenyl bromides in high efficiency with a wide range of group tolerance.

Photochemical Mn-Mediated Generation of Azide Radicals for Improvement of Alkene Hydroxyazidation.

State-of-the-art strategies for alkene-hydroxyazidation, which yield a mixture of ß-azido alcohol and ß-azido peroxide, must rely on phosphine reagents to improve the chemoselectivity. To overcome the above problems, we present a photochemical hydroxyazidation of alkenes via Mn-mediated ligand-to-metal charge transfer (LMCT) in O2, which activates N3- to •N3 and incorporates O2 to be used as an oxygen source in the hydroxyazidation products. Broad alkene range and step-economy chemistry for the hydroxyazidation transformation were also demonstrated.

Super-Stretchable and High-Energy Micro-Pseudocapacitors Based on MXene Embedded Ag Nanoparticles.

The advancement of aqueous micro-supercapacitors offers an enticing prospect for a broad spectrum of applications, spanning from wearable electronics to micro-robotics and sensors. Unfortunately, conventional micro-supercapacitors are characterized by low capacity and slopy voltage profiles, limiting their energy density capabilities. To enhance the performance of these devices, the use of 2D MXene-based compounds has recently been proposed. Apart from their capacitive contributions, these structures can be loaded with redox-active nanowires which increase their energy density and stabilize their operation voltage. However, introducing rigid nanowires into MXene films typically leads to a significant decline in their mechanical properties, particularly in terms of flexibility. To overcome this issue, super stretchable micro-pseudocapacitor electrodes composed of MXene nanosheets and in situ reconstructed Ag nanoparticles (Ag-NP-MXene) are herein demonstrated, delivering high energy density, stable operation voltage of ≈1 V, and fast charging capabilities. Careful experimental analysis and theoretical simulations of the charging mechanism of the Ag-NP-MXene electrodes reveal a dual nature charge storage mechanism involving ad(de)sorption of ions and conversion reaction of Ag nanoparticles. The superior mechanical properties of synthesized films obtained through in situ construction of Ag-NP-MXene structure show an ultra stretchability, allowing the devices to provide stable voltage and energy output even at 100% elongation.

An efficient tandem elimination-cyclization-desulfitative arylation of 2-(gem-dibromovinyl)phenols(thiophenols) with sodium arylsulfinates.

An efficient tandem elimination-cyclization-desulfitative arylation of 2-(gem-dibromovinyl)phenols(thiophenols) with sodium arylsulfinates has been developed. In the presence of TBAF-PdCl(2)-Cu(OAc)(2)-NEt(3), the reactions generated 2-arylbenzofurans(thiophenes) with good yields in one-pot under ligand-free conditions.

Controllable chemoselectivity in the coupling of bromoalkynes with alcohols under visible-light irradiation without additives: synthesis of propargyl alcohols and α-ketoesters.

The chemoselectivity of visible-light-induced coupling reactions of bromoalkynes with alcohols can be controlled by simple changes to the reaction atmosphere (N2 or O2). A N2 atmosphere favours propargyl alcohols via a direct C-C coupling process, whereas an O2 atmosphere results in the generation of α-ketoesters through the oxidative C[triple bond, length as m-dash]C/C-O coupling pathway.

Cycloaddition of alkynyl ketones with N-tosylimines catalyzed by Bu3P and DMAP: synthesis of highly functionalized pyrrolidines and azetidines.

Cycloadditions of alkynyl ketones with N-tosylimines catalyzed by Lewis bases to synthesize azetidines and pyrrolidines were systematically described. In the reaction of alkynyl ketones with N-tosylimines catalyzed by Bu3P at room temperature in toluene, highly functionalized pyrrolidines were formed in good to excellent yields. When DMAP was used in place of Bu3P as catalyst to facilitate the cycloaddition, completely substituted azetidines were produced in moderate to good yields in CH2Cl2. Both cyclization reactions proceeded smoothly with complete stereoselectivity. The scope and limitations of these cycloaddition reactions were also investigated.

Synthesis of Multisubstituted Furans via a Catalyst- and Additive-Free Tandem Reaction of Enynones with Sulfinic Acids in Water.

A facile and efficient tandem reaction of enynones with arylsulfinic acids was developed. A variety of multisubstituted furans were obtained in satisfactory yields via an O2-oxidative single-electron-transfer process without any catalyst and additive in water.

Visible-Light-Promoted Oxidative Amidation of Bromoalkynes with Anilines: An Approach to α-Ketoamides.

A convenient and practical synthetic route to α-ketoamides from bromoalkynes and anilines through phototriggered organic transformations via a C-N cross-coupling and an oxidation of C≡C was developed. The reaction could be furnished without an external photocatalyst at ambient conditions, and a wide range of α-ketoamides were obtained in good yields.

Visible-Light-Promoted [2 + 2 + 2] Cyclization of Alkynes with Nitriles to Pyridines Using Pyrylium Salts as Photoredox Catalysts.

A highly regioselective [2 + 2 + 2] cyclization of aromatic alkynes with nitriles is developed for the preparation of 2,3,6-trisubstituted pyridines under visible-light irradiation using a pyrylium salt as the photoredox catalyst. This cycloaddition is achieved through a photooxidative single-electron-transfer process at room temperature and under metal-free conditions. A variety of aromatic alkynes and nitriles are employed to furnish the annulation products in good yields.

(n)Bu3P-catalyzed desulfonylative [3 + 2] cycloadditions of allylic carbonates with arylazosulfones to pyrazole derivatives.

Highly efficient (n)Bu3P-catalyzed desulfonylative [3 + 2] cycloadditions of allylic carbonates with arylazosulfones were developed for the synthesis of pyrazole derivatives. The reactions proceed smoothly under mild conditions to generate corresponding annulation products in good to excellent yields.

DMAP-Catalyzed [2 + 4] Cycloadditions of Allenoates with N-Acyldiazenes: Direct Method to 1,3,4-Oxadiazine Derivatives.

An efficient DMAP-catalyzed [2 + 4] cycloaddition of allenoates and N-acyldiazenes is reported. The reaction involved embedding three heteroatoms into a six-membered ring and generated 1,3,4-oxadiazine derivatives in moderate to good yields.

Et3N-promoted tandem ring-opening reaction of N-tosylaziridines with terminal alkynoates: a straightforward synthesis of functionalized enamines.

A tandem ring-opening reaction of N-tosylaziridines with terminal alkynoates promoted by Et(3)N has been described. A variety of N-tosylaziridines reacted with terminal alkynoates to give functionalized enamines in moderate to good yields under simple reaction conditions.

PPh3-catalyzed unexpected alpha-addition reaction of 1-(o-hydroxyaryl)-1,3-diketones to terminal alkynoates: a straightforward synthesis of multifunctional vinylesters.

PPh3-catalyzed alpha-addition reactions of 1-(o-hydroxyaryl)-1,3-diketones to terminal alkynoates involving carbon-carbon bond cleavage to give multifunctional vinylesters are described.