DABCO-Promoted (3\n+ 2) Annulation of D–A Cyclopropanes\nwith Alkynoates for the Synthesis of Cyclopentenol Derivatives

Efficient synthesis of highly functionalized cyclopentenols\nwith\nan exocyclic Z double bond was investigated via a (3 + 2) annulation\nreaction of 2-aroyl-D–A (donor–acceptor) cyclopropanes\nwith alkynoates in the presence of DABCO. This synthetic approach\nfeatured a wide range of readily available 2-aroyl-substituted D–A\ncyclopropanes with diverse functional groups, densely substituted\ncyclopentenols with two stereogenic centers and an exocyclic double\nbond in a highly stereocontrolled manner and had operationally simple\nand mild reaction conditions.