Fig. 1. Chemical structure of the compounds used and their role in the Michael addition. (a) Structure of the substrates of the Michael addition (Malref3 and Pentref4), as well as the K2CO3 solubilizing phase-transfer catalysts used (NaPy 1 and UPy 2). (b) The catalytic activity and type of kinetics associated with each species in the K2CO3 catalyzed Michael addition, and the equilibria between UPy 2 (Kdim = 6 × 107 M–1 at 25 °C in CHCl3)28 and NaPy 1 (Ka = 5.2 × 105 M–1 for UPy 2 and NaPy 1 in CDCl3, see Fig. S2† for experimental results of binding constant determination by 1H NMR).
