Date of Award
Master of Science in Chemical Sciences (MSCB)
Christopher W. Alexander
Michael Van Dyke
Alkenylphosphonates (vinylphosphonates) are important targets for R & D because they have interesting chemical, biological and pharmacological properties. Vinylphosphonates are used in synthesis, polymer applications, and have demonstrated potential as anticancer and antimicrobial agents.
Vinyl triflates are useful in organic synthesis and are referred to as pseudo-halides because they react in a manner similar to halides. Vinyl triflates have a broad range of synthetic utility because they undergo nucleophilic substitutions and transition metal-mediated reactions. There is a growing interest in using α-phosphonovinyl pseudo-halides in transition metal-mediated cross-coupling reactions as a means to synthesize α, β-substituted alkenylphosphonates. Over the past three years, our group has developed a reliable synthesis of novel α-phosphonovinyl triflates from α-ketophosphonates and has been exploring the reactivity of these vinyl triflates.
Part I of this thesis describes the synthesis of 1-aryl-1-alkenyl phosphonates through an environmentally friendly Pd-mediated Suzuki reaction of α-phosphonovinyl triflates and aryl boronic acids. The cross-coupling reactions were completed using simple reaction conditions, green solvents (isopropyl alcohol/H2O), a heterogeneous catalyst with a very low mole loading (0.007%), and a benign base. The 1-aryl-1-alkenyl phosphonates were prepared in 72-98% yield after purification. Part II of this thesis describes the Pd-mediated reduction of α-phosphonovinyl triflates in the presence of formic acid as a new method to prepare β-substituted alkenylphosphonates in 64-90% yield.
Mensah, Ronald laryea, "Synthesis of α, β-Substituted Alkenylphosphonates from α-Phosphonovinyl Triflates: I) Palladium Catalyzed Suzuki-Miyaura Cross-coupling with Aryl Boronic Acids II) Palladium Catalyzed Reduction" (2017). Master of Science in Chemical Sciences Theses. 16.