Iridium-Catalyzed Asymmetric Addition of Thiophenols to Oxabenzonorbornadienes

A highly efficient asymmetric ring addition reaction of oxabenzo­norborna­dienes with thiophenols using an iridium/(<i>S</i>)-xyl-binap catalyst is developed. This catalyst system overcomes catalyst poisoning and background reactions and allows the formation of exclusive thiol addition products in high yields (up to 97% yield) with excellent enantioselectivities (up to 98% ee). Particularly noteworthy is that no competitive ring-opened side products are observed. X-ray crystal structure analysis confirmed the adduct is solely in the <i>exo</i>-configuration

Palladium/Silver-Cocatalyzed Tandem Reactions of Oxabenzonorbornadienes with Substituted Arylacetylenes: A Simple Method for the Preparation of 1,2-Diarylethanones and 1,2-Diarylacetylenes

The effective synthesis of 1,2-diarylethanones was achieved using palladium­(II) acetate [Pd­(OAc)₂] and silver triflate (AgOTf) as cocatalysts from various oxabenzonorbornadiene derivatives and substituted arylacetylenes via tandem reactions under mild conditions. Exploration of the oxabenzonorbornadiene substrates showed that the 1,2-diarylacetylenes were obtained from adjacent alkoxy substituted oxabenzonorbornadiene derivatives. Preliminary mechanistic studies indicate that the AgOTf served as an indispensable catalyst, and the mechanism of the tandem reaction was proposed

Rh-Catalyzed Highly Enantioselective Hydroalkynylation Reaction of Norbornadiene Derivatives

The complexes of various Rh precusors with ferrocenyl chiral ligand (<i>R</i>,<i>S</i>)-Cy₂PF-PPh₂ were found effective catalysts for the asymmetric hydroalkynylation reaction of norbornadiene derivatives. When RhCl₃·3H₂O was employed, good yields (up to 98%) and high enantioselectivities (up to >99.9% <i>ee</i>) could be obtained for the reactions of a broad scope of substrates