Highly E-selective solvent-free Horner-Wadsworth-Emmons reaction catalyzed by DBU

The solvent-free Horner-Wadsworth-Emmons reaction of triethyl phosphonoacetate with a variety of aldehydes was catalyzed by DBU in the presence of K2CO3 to give E-alpha, beta-unsaturated esters highly selectively (99 : 1 for most of the reactions). The reaction with ketones gave trisubstituted olefins with good to high E-selectivity by DBU-Cs2CO3.