Alexander Kvitsinski Rose Hills
Development of Difluorobenzyl Synthons for Cross-Coupling Chemistry
The benzylic methylene unit (Ar-CH2-R) is a common motif in drug candidates and pharmaceuticals. However, the propensity of its C-H bonds toward oxidation creates the challenge of metabolic stability. One solution is the substitution of this motif with the benzylic difluoromethylene or difluorobenzyl units (Ar-CF2-R), wherein the reactive C-H bonds are substituted with metabolically more stable C-F bonds. However, despite the potential advantage of such an approach, few pharmaceuticals containing this motif have been commercialized. This project focuses on the development of novel Ar-CF2-M synthons for C-C cross-coupling chemistry. First, the substrate scope of the difluorocarbene insertion into Au(I)-aryl bonds will be investigated. We envision that a variety of aryl and heteroaryl-Au(I) species can undergo the difluorocarbene insertion. Secondly, conditions to couple these synthons with sp2-electrophiles will be screened and optimized. Lastly, the mechanism of the formal difluorocarbene insertion and the stability of the new aryldifluoromethyl-Au(I) species will be investigated through experimental and computational studies. This will assist the development of similar synthons involving cheaper metals such as copper, avoiding use of the precious metal gold.