Hyunik Shin

Nucleophilic Fluorination of Triflates by Tetrabutylammonium Bifluoride

Careful examination of nucleophilicity, basicity, and leaving group ability led us to discover the nucleophilic fluorination of triflates by weakly basic tetrabutylammonium bifluoride, which provides excellent yields with minimal formation of elimination-derived side products. Primary hydroxyl groups as well as secondary hydroxyl groups in acyclic chains or in five-membered rings are excellent substrates, whereas benzylic and aldol-type secondary hydroxyl groups give poor yields as a result of the instability of their triflates.

A new type of self-supported, polymeric Ru-carbene complex for homogeneous catalysis and heterogeneous recovery: synthesis and catalytic activities for ring-closing metathesis

A novel 2nd generation Grubbs-type catalyst tethering an isopropoxystyrene has been synthesized and automatically polymerized in solution to form a self-supported polymeric Ru-carbene complex, which catalyzed ring-closing metathesis homogeneously, but was recovered heterogeneously.

A Stereodivergent Synthesis of Hydroxyethylene Dipeptide Isostere via Highly Diastereoselective Epoxidation

Epoxidation of δ-amino-β,δ-unsaturated ester with trifluoroperacetic acid afforded its epoxide in a highly diastereo- H selective manner. Subsequent stereodivergent epoxide opening reactions provided synthetic routes towards both the threo and erythro hydroxyethylene peptide isostere.