Synthesis of a Chiral Phosphacycle to Catalyze Deoxygenative Condensation of α-Keto Esters and Carboxylic Acids via P(III)/P(V) Redox Cycling
Open Access
Author:
Yan, Patrick Kemo
Area of Honors:
Chemistry
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Alexander Thomas Radosevich, Thesis Supervisor Przemyslaw Maslak, Thesis Honors Advisor Katherine Mary Masters, Faculty Reader
Keywords:
Phosphorus redox
Abstract:
Previous studies by the Radosevich Group have shown that a phosphetane (i.e. a 4-membered phosphacycloalkane) catalyzes the deoxygenative condensation of α-keto esters and carboxylic acids to form α-acyloxy ester products with good functional group compatibility. The reaction proceeds through initial addition of the phosphacycle in its +3 oxidation state to the α-keto ester in a Kukhtin-Ramirez reaction, followed by subsequent reaction with the carboxylic acid to expel a phosphine oxide byproduct with C-O bond formation. The phosphine oxide, which has phosphorus in the +5 oxidation state, is then reduced in situ by a silane reductant back to the starting phosphetane. This thesis describes initial experiments directed toward enantioselective variants of this catalytic reaction using new, chiral phosphacycles as catalysts.
