Progress Toward the Total Synthesis of the Epoxyquinoid Family of Natural Products

Download or read book Progress Toward the Total Synthesis of the Epoxyquinoid Family of Natural Products written by and published by . This book was released on 2007 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enyne metathesis is a powerful C-C bond forming reaction that combines an alkene and an alkyne and forms a conjugated 1,3-diene. The scope of enyne metathesis was expanded by combining various alkynes with vinyl ethers. Typically vinyl ethers are poor metathesis substrates, but a method was developed for the synthesis of dienol ethers utilizing ruthenium carbenes. The products of these reactions were subjected to [4+2] cycloaddition conditions to give substituted cyclohexene rings. The epoxyquinoid family is a highly targeted series of natural products. A general method for the synthesis of the core structure of these natural products has been explored. An enyne cross metathesis/ring closing metathesis step was designed as the key reaction to this synthesis. A Darzen's condensation between a chiral [alpha]-alkoxy aldehyde and a chloroacyl oxazolidinone was successfully employed to join two fragments of the molecule as well as to install an epoxide. A highly diastereoselective cuprate addition set the stereochemistry of the first stereogenic center. The early intermediates were prepared via easily scalable organic syntheses procedures including utilizing a carbohydrate as the source of chirality. Ring closing enyne metathesis to form the epoxyquinoid core was evaluated in two epimeric series.