 Upon addition of a diethyl vinylphosphate derivative (5) to the Michael adduct, a domino Michael reaction and Horner-Wadsworth-Emmons reaction occurs due to the phosphonate group produced from (5) to give an ethyl cyclohexenecarboxylate derivative along with two unwanted by-products.To transform the undesired by-products into the desired ethyl cyclohexencarboxylate derivative, the mixture of the product and by-products was treated with Cs2CO3 in ethanol.This induced a retro-Michael reaction on one by-product and a retro-aldol reaction accompanied with a Horner-Wadsworth-Emmons reaction for the other.