Potassium phosphate–ionic liquid mediated selective mono-Michael addition

Abstract

A process for exclusive mono-Michael addition of active methylene compounds to conjugated esters, nitriles and ketones is developed. An ionic liquid-mediated reaction is carried out at room temperature. A reaction carried out at 60 °C resulted in a double-addition. A mechanism is proposed and supported by P31 and DOSY NMR analysis.

Development of Intermediates for High‐Energy Content New Biomass‐Derived Jet and Diesel Fuels with a Robust Rapid Green Reaction

“…Therefore, the reaction might not be initiated if additional K 3 PO 4 ·3H 2 O was not added in the second round. The results are different from the previous work reported by Sawant et al,[31a] although the proposed mechanisms of both works are similar to each other. In the previous work by Sawant et al, a large amount of K 3 PO 4 (0.5 equiv) was required for recycle experiments (three times).…”

“…A plausible mechanism for this reaction is presented in Supporting Information Figure S1. Based on the assumption and recently reported mechanisms of Michael addition reactions with potassium phosphate as the base, phosphate acts as the base and extracts a proton from the active Michael donors. The formed organic anion then exchanges the counter ion with TBAB to afford an ion pair, which is the key step in this reaction, as the ion pair could enter into the organic phase to react with Michael acceptors .…”

“…Based on the assumption and recently reported mechanisms of Michael addition reactions with potassium phosphate as the base, phosphate acts as the base and extracts a proton from the active Michael donors. The formed organic anion then exchanges the counter ion with TBAB to afford an ion pair, which is the key step in this reaction, as the ion pair could enter into the organic phase to react with Michael acceptors . Moreover, water can enhance the electrophilicity of β‐carbon of the α,β‐unsaturated carbonyl compound as reported by Khatik et al Water can also form hydrogen bonds with Michael donors and acceptors, thus affording a transition state.…”