A facile and highly diastereoselective synthesis of carbocyclic spiro-pyrazolones via DABCO catalyzed Michael-Michael domino reaction

An efficient domino Michael-Michael reaction of ω- and δ-nitro α,β-unsaturated esters with alkylidenepyrazolones has been accomplished using DABCO as the organocatalyst under mild reaction conditions. Under the present organocatalytic method, a wide range of carbocyclic spiro-pyrazolones with three tertiary stereogenic centers and a quaternary stereocenter has been prepared in high yields and excellent diastereoselectivities. An ester and nitro groups present in the spiro-pyrazolones have been utilized for further structural transformations.