Enantioselective synthesis through catalytic metathesis

An efficient metal-catalyzed process that converts styrenyl ethers to 2-substituted chromenes is described. This class of reactions may be carried out on either terminal or disubstituted styrenyl substrates. Depending on the level of substitution of the olefins, the Ru-catalyst may initiate reaction by interaction with either the styrenyl or carbocyclic alkene. Metal-catalyzed rearrangements, performed under an ethylene atmosphere, provide monomeric products in excellent yields. The presence of ethylene is crucial to reaction efficiency. Mechanistic data that rationalize these observations are provided. A variety of styrenyl ethers are available in the optically pure form through Zr-catalyzed kinetic resolution, allowing several 2-substituted chromenes to be prepared in high enantiomeric purity.*; An investigation of enantioselective synthesis of five and six-membered carbo- and heterocycles through catalytic metathesis is described. Cyclic alkenes can be synthesized with high optical purity and efficiency through catalytic kinetic resolution or desymmetrization using chiral Mo-complexes. Mechanistic and transition state arguments are provided.*; The first catalytic enantioselective ring-opening/cross metathesis reaction is disclosed. This process allows for the synthesis of optically pure compounds in nearly quantitative yields with complete control of olefin stereochemistry. Issues related to substrate scope, reaction mechanism and selectivity will be addressed.*; *Please refer to dissertation for diagrams.