Yudao Ma

A base-mediated silylation reaction leading to benzyl silanes has been developed. Under transition-metal and solvent free conditions, the silylation of a wide array of p-quinone methides is achieved using a Cs₂CO₃ catalyst in yields up to 96%. Carboxylation of the as-obtained organosilane with gaseous CO₂ provides a new synthetic protocol for the preparation of carboxylic acid.

Organic azides are synthetically and commercially useful intermediates with a wide variety of applications. In this work, azidative aromatization of quinone methides under transition metal and acid‐free conditions can avoid the forming of highly toxic and explosive hydrazoic acid and azide salts. The use of cesium carbonate as a catalyst and water as an effective additive, elimination of a transition metal catalyst, reaction solvent, and column chromatography separation led to an overall greener approach to access valuable benzyl azides in quantitative yields. Because the procedure can be used to prepare a serious of benzyl azides without contamination by any harmful transition metal residues, this new method has great potential in pharmaceutical synthesis and chemical biology studies.

The introduction of trifluoromethyl groups into organic molecules has attracted great attention in the past five years. In this review, we describe the recent efforts in the development of trifluoromethylation via copper catalysis using nucleophilic, electrophilic or radical trifluoromethylation reagents.

A transition metal-free enantioselective 1,2-silylation of aromatic aldehydes to yield chiral α-hydroxysilanes was developed for the first time.

A robust chiral N-heterocyclic carbene precursor based on [2.2]paracyclophane was designed and synthesized for a highly enantioselective metal-free catalytic boration. Enantioselective 1,4-addition of a commercially available bis(pinacolato)diboron (B 2 (pin) 2) to chalcones was achieved by using the new bifunctional chiral carbene as catalyst, affording the corresponding products in up to 99% yield and 97% enantiomeric excess. Moreover, it was found that water used as the additive plays a key role in the carbene-catalyzed enantioselective boration.

A new series of chiral bicyclic 1,2,4-triazolium salts with various substituents in the pseudo-ortho position of the [2.2]paracyclophane skeleton has been successfully synthesized and applied to enantioselective α-silylations of N-tosylaldimines. The dual role of the new carbene precursor as an organocatalyst and as a ligand of the copper catalyst in the asymmetric silylation were investigated. The chiral carbene–copper catalyst has significant advantages over its carbene counterpart as an organocatalyst, affording the corresponding α-silyl amines in 77–99% yields over 20 examples and with 76–98% ee. In addition, the transannular electronic effects of the substituents in the pseudo-ortho position of the [2.2]paracyclophane skeleton were also discussed.

Copper( i )-catalyzed azide–alkyne cycloaddition (CuAAC) provides an efficient synthesis of 1,4-disubstituted 1,2,3-triazoles. This feature article highlights the recent progress on the regisoselective synthesis of multisubstituted 1,2,3-triazoles, which current click reaction (CuAAC) is unable to do.

A copper(I)-catalyzed tandem CuAAC/alkynylation reaction of various alkynes, organic azides, and bromoalkynes to provide rapid access to 5-alkynyl-1,2,3-triazoles has been developed. The reaction proceeded via a copper-catalyzed alkyne azide cycloaddition followed by interception of the in situ formed cuprate–triazole intermediate with bromoalkyne. This reaction offers a new method to afford fully substituted triazoles in high yields with complete regioselectivity under mild reaction conditions.