Asymmetric Catalytic Reactions of Donor-Acceptor Cyclopropanes.

Due to the synergistic "push-pull" effect of vicinal electron-donating and electron-withdrawing groups, donor-acceptor (D-A) cyclopropanes have been recognized as one of the most powerful building blocks to generate polyfunctional reactive intermediates after a strain-driven ring cleavage. Enantioselective reactions of D-A cyclopropanes provide an efficient approach to enantioenriched acyclic and cyclic compounds. A number of chiral Lewis/Brønsted acids, transition metals, and organocatalysts have been designed for such transformations, including ring-openings, annulations, and rearrangements. This minireview highlights the developments and new advances in this field and describes new synthetic opportunities offered by these interesting methodologies.