Asymmetric Catalysis of Diels–Alder Reaction

The Diels–Alder (DA) reaction (or “diene synthesis”) between a diene and a dienophile generates two s bonds stereoselectively and up to four chiral centers in a single step to afford six-membered cyclic compounds. This cycloaddition reaction named after Professor Otto Paul Hermann Diels (1876–1954) and his student Kurt Alder (1902–1958) was discovered in 1928 during studies on the reaction of benzoquinone with cyclopentadiene (Scheme 1.1) [1, 2], and has become an extremely useful and classicmethodology in organic synthesis. For their discovery, Diels and Alder received the Nobel Prize in chemistry in 1950. Since this landmark discovery, great progress in the area has been achieved and the historical development for the past 80 years can be divided into three periods: (i) from the discovery to the 1950s, the studies mainly focused on the substrate scope and mechanism research, and one of the representative works was the Alder endo rule; (ii) from the 1950s to the 1970s, the DA reaction was successfully applied to the total synthesis of many complex molecules, and two important theories [molecular orbital theory (Woodward-Hoffmann rule) and frontier orbital theory (Kenichi Fukui)] were applied to explain the mechanism; (iii) from the 1980s to the present day, the exploration and application of an enantioselective version of DA reactions have attracted tremendous interest from chemists [3].