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An atom-economic protocol for the efficient and highly chemo- and stereoselective trans-hydroarylation of ynamides with hydroxyarenes catalyzed by B(C6F5)3has been developed. Use of readily available starting materials, low catalyst loading, mild reaction conditions, a broad substrate scope, ease of scale-up, and versatile functionalizations of the enamide products make this approach very practical and attractive.

For nearly 60 years, significant research efforts have been focused on developing strategies for the cycloaddition of bicyclobutanes (BCBs). However, higher-order cycloaddition and catalytic asymmetric cycloaddition of BCBs have been long-standing formidable challenges. Here, we report Pd-catalyzed ligand-controlled, tunable cycloadditions for the divergent synthesis of bridged bicyclic frameworks. The dppb ligand facilitates the formal (5+3) cycloaddition of BCBs and vinyl oxiranes, yielding valuable eight-membered ethers with bridged bicyclic scaffolds in 100% regioselectivity. The Cy-DPEphos ligand promotes selective hetero-[2σ+2σ] cycloadditions to access pharmacologically important 2-oxabicyclo[3.1.1]heptane (O-BCHeps). Furthermore, the corresponding catalytic asymmetric synthesis of O-BCHeps with 94–99% ee has been achieved using chiral (S)-DTBM-Segphos, representing the first catalytic asymmetric cross-dimerization of two strained rings. The obtained O-BCHeps are promising bioisosteres for ortho-substituted benzenes.

A highly monoselective synthesis of ferrocenyl alkynes was achieved via Cu-promoted ferrocene C(sp2)–H bond activations. The reaction employs an 8-aminoquinoline group as the directing group and terminal alkynes as the alkyne source. It was found the alkynylation products actually complex with the in situ generated Cu(I) ions to give robust and stable alkyne π-copper complexes. In addition, these alkyne π-copper complexes could be freed of the copper ions to give various ferrocenyl alkynes in almost quantitative yields. The test results also showed that the alkyne π-copper complexes could be reformed from the free alkynes upon treating them with Cu(I) salts.

The direct use of ammonia in transition-metal promoted C–H bond amination for the synthesis of primary amines is considered to be one of the major challenges in synthetic organic chemistry. Herein, we report that such transformation can be successfully achieved via nickel-promoted amination of inert arene C–H bonds with ammonia gas assisted by an 8-amino-quinoline directing group.