A palladium-catalyzed, iodine-mediatedelectrophilicannulation between 2-(1-alkynyl)biphenyl and disulfide has been developed. With the combination of PdCl2 and I2, a variety of 2-(1-alkynyl)biphenyls underwent electrophilicannulations with various disulfides successfully to afford the corresponding 9-sulfenyl phenanthrenes in moderate to excellent yields.
We describe a novel and highly efficient metal-free strategy to construct 9,9-disubstituted fluorenes and phenanthrenes via the TfOH-catalyzed cycloisomerizations of o-alkynylbiaryls. Notably, the significant effects of the electronic properties and steric hindrance of the alkyne terminus on the reaction selectivity have been observed.
Transition metal-free hydroarylation of unactivated alkynes was achieved by combining a Brønsted acid catalyst and a two-phase solvent system consisting of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) and cyclohexane. This protocol is applicable to a wide variety of 2-alkynylbiaryls which leads to the synthesis of substituted phenanthrenes via 6-endo-selective ring closure. The biphasic system achieves
Here we demonstrate that merging photoredox catalysis with Lewisacidcatalysis provides fundamentally newactivationmode of C-C triple bond to achieve the bond-forming reaction of alkynes with weak nucleophiles....
effective protocol for the synthesis of the phenyl ring in excellent yields with nice functional group tolerance. In this transformation, the Cu(OTf)2 catalyst plays a key role in the conversion of alkyne moiety into an alkene-type moiety, which means that the dienyne reactant is converted into a triene-type substrate. Thus, this reaction proceeds via a Cu(II)-catalyzed 6π-photocyclization of triene-type