Silver-Catalyzed Isocyanide-Isocyanide [3+2] Cross-Cycloaddition Involving 1,2-Group Migration: Efficient Synthesis of Trisubstituted lmidazoles.

Imidazole ring is an important five-membered aromatic heterocycle that is widely present in natural products and synthetic molecules. The isocyanide-isocyanide [3+2] cross-cycloaddition reaction constitutes a straightforward method to access imidazoles starting from the easily available chemicals. So far, only three successive reports are known and all lead to the formation of 1,4-disubstituted imidazoles.

Tandem O-H Insertion/[1,3]-Alkyl Shift of Rhodium Azavinyl Carbenoids with Benzylic Alcohols: A Route To Convert C-OH Bonds into C-C Bonds.

Alcohols are among the most abundant and commonly used organic feedstock in industrial processes and academic research. The first tandem O-H insertion/[1,3]-alkyl shift reaction reported is between benzylic alcohols and rhodium azavinyl carbenoids derived from N-sulfonyl-1,2,3-triazoles, which provides a strategically novel way of cleaving C-OH bonds and forming C-C bonds. The substrate scope is broad, capable of covering 1°-, 2°-, and 3°-benzylic alcohols.

Chemo- and regioselective reductive deoxygenation of 1-en-4-yn-ols into 1,4-enynes through FeF3 and TfOH co-catalysis.

We report chemo- and regioselective direct reductive deoxygenation of 1-en-4-yn-3-ols into 1,4-enynes through FeF3 and TfOH cooperative catalysis under NBSH-mediated conditions. Further, we show the efficient synthesis of a pharmaceutically significant 1,4-enyne. The present methodology can also be used for chemo- and regioselective direct deoxygenation of other alcohols.

Catalytic σ-activation of carbon-carbon triple bonds: reactions of propargylic alcohols and alkynes.

The majority reactions of alkynes in the literature are reported to proceed via either structural σ-activation or catalytic π-activation of C≡C bonds. We skillfully designed novel methods for the catalytic σ-activation of C≡C bonds of alkynyl compounds. For terminal alkynyl compounds, σ-activation was achieved by silver(i)-catalyzed C-H functionalization.

Synthesis of 4-Ynamides and Cyclization by the Vilsmeier Reagent to Dihydrofuran-2(3H)-ones.

The room-temperature nucleophilic addition of vinyl azides to propargylic alcohols under BF3·Et2O catalysis provides an efficient synthesis of 4-ynamides. The procedure is operationally convenient, shows broad substrate scope, and is viable for the synthesis of multifunctional 4-ynamides. Further, a Vilsmeier intramolecular cyclization of 4-ynamides into dihydrofuran-2(3H)-ones has also been discovered, which represents the first report of alkynes being used as the nucleophiles in Vilsmeier-type reactions.

Iodobenzene catalyzed C-H amination of N-substituted amidines using m-chloroperbenzoic acid.

The oxidative C-H amination of N"-aryl-N'-tosyl/N'-methylsulfonylamidines and N,N'-bis(aryl)amidines has been accomplished using iodobenzene as a catalyst to furnish 1,2-disubstituted benzimidazoles in the presence of mCPBA as a terminal oxidant at room temperature. The reaction is general, and the target products can be obtained in moderate to high yields.

Pd-catalyzed C-H activation/C-N bond formation: a new route to 1-aryl-1H-benzotriazoles.

A method for the C-H activation of aryl triazene compounds followed by intramolecular amination is described. It involves the use of a catalytic amount of Pd(OAc)(2) that efficiently effects the cyclization to provide 1-aryl-1H-benzotriazoles at moderate temperature.