Cu2O-catalyzed cascade phosphinylation/cyclization of 2'-aminochalcones for the synthesis of hemi-indigo derivatives.

A Cu2O-catalyzed cascade phosphinylation/cyclization reaction of 2'-aminochalcones and diphenylphosphine oxides to produce hemi-indigo derivatives has been developed. This strategy facilitates the sequential formation of a C-P bonds and a C-N bond in a single reaction step. Notably, the approach features one-pot operation, an earth-abundant copper catalyst, readily available starting materials, a broad substrate scope and high compatibility with functional groups, providing 33 compounds in acceptable yields.

Synthesis of pyrazoles from sulfonyl hydrazone and benzyl acrylate under transition-metal-free conditions.

Pyrazoles as an important class of heterocyclic compounds, are widely found in pharmaceuticals and bioactive natural products. Herein we report a [3 + 2] cycloaddition reaction for the synthesis of a series of pyrazoles, with the yield up to 77%. This approach exhibits many notable features, such as convenient operating conditions, excellent functional group compatibility and readily accessible raw materials, providing an alternative route for the construction of pyrazole derivatives.

C-H Borylation of Benzophenones Using Hydrazone as the Traceless Directing Group.

C-H borylation is one of the powerful C-H bond functionalization reactions. In this context, a metal-free C-H borylation of benzophenones using hydrazone as the traceless directing group has been reported. The dibromoboron intermediates can be obtained in excellent yields, and the corresponding arylboronic esters are generated in moderate to excellent yields. Furthermore, the borylated compounds can be transformed in a one-pot method, avoiding the loss of overall yield caused by the separation of the arylboronic esters.

Metal-Free Boron-Mediated ortho-C-H Hydroxylation of N-Benzyl-3,4,5-tribromopyrazoles.

A novel route has been reported for C-H hydroxylation of benzyl compounds directed by a 3,4,5-tribromopyrazole auxiliary via boronation/oxidation using BBr3 and NaBO3·4H2O. The strategy exhibits outstanding site selectivity and affords the corresponding phenols in moderate to excellent yields under metal-free conditions. Besides, this protocol can be achieved in one pot, which is highly promising as a practical method for use in a multistep organic synthetic process.

Adamantane-1-Carbonyl-Directed C-H Borylation and Hydroxylation of Benzenethiols.

A novel route has been described for C-H borylation and hydroxylation of benzenethiols directed by adamantane-1-carbonyl using BBr3. The protocol generates corresponding arylboronic esters and phenols in moderate to excellent yields under metal-free conditions. In addition, the borylated product can be transformed and the directing group can be removed in good yields, which will facilitate the synthesis of structurally diverse benzenethiols.