Lewis Acid Mediated Cyclizations: Diastereoselective Synthesis of Six- to Eight-Membered Substituted Cyclic Ethers.

Cyclic ethers are widely abundant in natural products. Cyclic ether templates are also utilized in drug design and medicinal chemistry. Although the synthetic processes for this class of compounds have been studied extensively with respect to five- and six-membered rings, medium-sized cyclic ethers are synthetically more challenging due to a variety of factors.

Mild, Selective Sulfoxidation with Molybdenum(VI) -Dioxo Catalysts.

Three molybdenum(VI) -dioxo catalysts (-) were synthesized with the goal of developing stable and selective oxidation catalysts for sulfoxidation. Their reactivities were investigated with a variety of substrates. We have demonstrated the usefulness of these catalysts for the chemoselective sulfoxidation of sulfides in the presence of reactive moieties, which has important applications for total synthesis processes.

Stereoselective Synthesis of Substituted Oxocene Cores by Lewis Acid Promoted Cyclization.

Substituted oxocene derivatives have been synthesized by Lewis acid catalyzed reactions of ε-hydroxyalkene and substituted aromatic aldehydes. The Cu(OTf)2-bis-phosphine catalyzed reaction typically provides substituted dihydropyran derivatives through an olefin migration followed by a Prins cyclization. The corresponding reaction catalyzed by TMSOTf or BF3·OEt2 provided eight-membered cyclic ethers (oxocenes), selectively.