Di-tert-Butyl Acetylenedicarboxylate and Its Cyclotrimerization

Di-tert—butylacetylenedicarboxylate (1)—surprisingly not synthesized before—is remarkable from a chemical standpoint. Its cyclotrimerization shows that the tert-butyl groups do not exert strong steric hindrance. Ready cleavage (without base) of the esters obtained from (1) is of advantage.