Synthesis of Strained 1,3-Diene Macrocycles via Copper-Mediated Castro–Stephens Coupling/Alkyne Reduction Tandem Reactions

Copper-catalyzed deacetonative Sonogashira coupling

A convenient Pd- and phosphine-free protocol for assembling internal alkynes from tertiary propargyl alcohols and (het)aryl halides has been developed. The proposed tandem approach includes the base-promoted retro-Favorskii fragmentation followed by Cu-catalyzed C(sp)-C(sp²) cross-coupling. The use of inexpensive reagents (e.g. a catalyst, additives, a base, and a solvent) and good functional group tolerance make the procedure practical and cost-effective. The synthetic utility of the method was demonstrated by a smooth alkynylation of vinyl iodides derived from natural steroidal hormones.

Recent advances in catalytic synthesis of medium-ring lactones and their derivatives

In light of the ever-increasing significance of medium-sized lactones across the range of chemical sciences, this review summarizes the recent advances in catalytic synthesis of medium-ring lactones with emphasis on reaction scope and mechanism.

Synthesis of [2]Catenanes by Intramolecular Sonogashira-Type Reaction

The catalytic activity of macrocyclic phenanthroline-CuI complexes was utilized to synthesize [2]catenanes by intramolecular Sonogashira-type reaction. The high reactivity of the acyclic starting material was critical to synthesize the [2]catenane in acceptable yields. The relationship between the yield of the [2]catenane and the structure of the starting materials was disclosed.

Synthesis of a 1,3-Bridged Macrobicyclic Enyne via Chemoselective Cycloisomerization Using Palladium-Catalyzed Alkyne-Alkyne Coupling

A unique intramolecular Pd-catalyzed alkyne-alkyne coupling is presented. This transformation generates a strained, 1,3-bridged, macrocyclic enyne. The process was readily executed on gram scale, and the structure of the product was elucidated via X-ray crystallographic analysis. A mechanistic rationale for the observed chemoselectivity is provided.