A new efficient method for the synthesis of carboacyclic nucleosides as biologically interesting compounds via aza-conjugate addition of pyrimidine nucleobases to alpha,beta-unsaturated esters in the presence of catalytic amount of LiOH center dot H2O (1.2-4.8 mol%) under microwave irradiation is described. This method affords the title compounds in good to excellent yields and in short reaction times. [GRAPHICS]