Wadsworth-Emmons Chemistry (Carbon-Carbon Double Bond Synthesis)

Recent developments in the biological function and medicinal application of retinoids and carotenoids has sparked a renewed interest in the stereoselective synthesis of polyenes. Most notably, in the development of reliable methods for the stereoselective synthesis of dienes and polyenes which contain (Z)-alkenes. The availability of pure (Z)-isomeric polyenes is indispensable in both the study of biological function and unambiguous identification of compounds isolated from natural sources.

This project studies is aimed at the synthesis, characterization and development of new fluorinated and bulky non-fluorinated bisphosphonate reagents to accomplish the stereoselective synthesis of (Z)-olefins in conjugated dienes and polyenes. Inherent in their structure are elements of organophosphorus reagents which produce (Z)-olefin formation in the synthesis of compounds which contain isolated double bonds. The bisphosphonates when incorporated at strategic sites in molecules should allow the stereoselective synthesis of conjugated dienes and polyenes containing (Z)-olefins. Additionally, the proposed vinyl phosphonates formed from the bisphosphonates will resolve difficulties in the chemical synthesis of bis(2,2,2-trifluoroethyl) phosphonates, compounds that are difficult to obtain by more traditional organophosphorus synthetic methods. Also, the resulting vinyl phosphonates should allow easy access to allylic phosphonates. These are important precursors to conjugated dienes and polyenes although their syntheses often present several experimental difficulties. Therefore, the proposed bisphosphonates are expected to complement the existing ensemble of methods for the synthesis of dienes and polyenes by providing a means to stereoselectively synthesize these compounds containing (Z)-olefins.