Phosphine-Catalyzed 1,2-cis-Diboration of 1,3-Butadiynes

Trialkyl phosphines PMe3 and PEt3 catalyze the 1,2-cis-diboration of 1,3-butadiynes to give 1,2-diboryl enynes. The products were utilized to synthesize 1,1,2,4-tetraaryl enynes using a Suzuki-Miyaura protocol and can readily undergo proto-deborylation.

Highly selective cross-coupling reactions of 1,1-dibromoethylenes with alkynylaluminums for the synthesis of aryl substituted conjugated enediynes and unsymmetrical 1,3-diynes

A highly efficient method for the synthesis of aryl substituted conjugated enediynes and unsymmetrical 1,3-diynes via selective cross-coupling reactions of 1,1-dibromoethylenes with alkynylaluminums using the Pd(OAc)2-DPPE and Pd2(dba)3-TFP complexes as catalysts, respectively, has been successfully developed. Though the alkyl substituted conjugated enediynes and unsymmetrical 1,3-diynes were not obtained, this case is also remarkable as the same starting materials could selectively produce either aryl substituted conjugated enediynes or unsymmetrical 1,3-diynes in moderate to excellent yields (up to 99%) in the different Pd-phosphine catalytic systems.

Palladium-catalyzed cross-coupling reaction of alkenyl aluminums with 2-bromobenzo[b]furans

Highly efficient and simple cross-coupling reactions of 2-bromobenzo[b]furans with alkenylaluminum reagents for the synthesis of 2-alkenylbenzo[b]furan derivatives using PdCl₂ (3 mol%)/XantPhos (6 mol%) as catalyst are reported. Excellent yields (up to 97%) were obtained for a wide range of substrates at 80 °C for 4 h in DCE.

PdCl₂ (3 mol%)/XantPhos (6 mol%) complexes was found to be a highly efficient catalyst for the synthesis of 2-alkenylbenzo[b]furans from 2-bromobenzo[b]furans and alkenylaluminums. The reaction was also found to be effective in gram-scale synthesis.

Photochemical Dual-Catalytic Synthesis of Alkynyl Sulfides

A photochemical dual-catalytic cross-coupling to form alkynyl sulfides via C(sp)-S bond formation is described. The cross-coupling of thiols and bromoalkynes is promoted by a soluble organic carbazole-based photocatalyst using continuous flow techniques. Synthesis of alkynyl sulfides bearing a wide range of electronically and sterically diverse aromatic alkynes and thiols can be achieved in good to excellent yields (50-96 %). The simple continuous flow setup also allows for short reaction times (30 min) and high reproducibility on gram scale. In addition, we report the first application of photoredox/nickel dual catalysis towards macrocyclization, as well as the first example of the incorporation of an alkynyl sulfide functional group into a macrocyclic scaffold.