Compositional Effect in AuPd Bimetallic Nanoparticles Towards Product Selectivity during Aerobic Oxidation of α-Hydroxy Esters and Phosphonates

Abstract

Aerobic oxidation of a-hydroxy esters and phosphonates for direct formation of a-keto esters and a-keto phosphonates was explored using Au nanoparticle based catalytic systems. Alloying Au with Pd resulted in high activity and selectivity for the aerobic oxidation reaction under base and solvent free conditions. The formation of desired a-keto esters and a-keto phosphonates as sole products were highly dependent on the composition of the alloy nanocatalyst. Addition of a secondary oxidizer such as tert-butylhydroperoxide (TBHP) significantly enhanced the yield of the products at shorter reaction time under mild reaction conditions.

Green and Effective Preparation of α-Hydroxyphosphonates by Ecocatalysis

“…They are especially useful as biologically active compounds such as antibiotics (e.g., Valinophos I [ 13 ], and Fosfazinomycin A III [ 14 ]); enzyme inhibitors (e.g., renin inhibitors II [ 15 ], for potential treatment of hypertension and congestive heart failure or neuraminidase inhibitor [ 16 ], for treatment of influenza infection, commonly called “the flu”); antiparasitics (e.g., inhibitors of Plasmodium falciparum growth IV [ 17 ], useful in treatment of malaria that is caused by this parasite); and insecticides (e.g., trichlorfon V ) ( Figure 1 ). Additionally, α-hydroxyphosphonic acids and their esters are very useful scaffolds in organic synthesis often used to prepare more complex molecules [ 18 ], e.g., after O -allylation and subsequent RCM or isomerization/Claisen rearrangement [ 19 ], reaction with primary amines leading to α-aminophosphonates and phosphonic acids [ 20 ], phospha-Brook rearrangement [ 21 ], reduction [ 22 ], halogenation [ 23 ], and oxidation leading to ketophosphonates ( Figure 1 ) [ 24 ].…”