Addition Reactions: Cycloaddition

This chapter contains sections titled: (2 + 2)-Cycloaddition (2 + 3)-Cycloaddition (2 + 4)-Cycloaddition Miscellaneous References The recent developments of the enantioselective gold(I)-catalysed cycloaddition reactions (2+2, 3+3, 4+2, and 4+3) have been extensively reviewed. The mechanisms of transition-metal-catalysed (2+2)–cycloaddition reactions between bicyclic alkenes and alkynes have been thoroughly reviewed. The rutheniumcatalysed asymmetric (2+2)–cycloaddition reactions of chiral acyl camphorsultamsubstituted alkynes with bicyclic alkenes formed bicyclic cyclobutenes with good yields and enantioselectivity. The formal (2+2)– cycloaddition is thought to involve an initial (3+2)–cycloaddition. Chiral air-stable ferrocenylphosphines promote the asymmetric (3+2)–cycloaddition of Morita-Baylis-Hillman carbonates with maleimides to form multifunctional cyclopentenes in reasonable yield and enantioselectivity. A review of the use of organocatalysts in the (3+2)–cycloaddition reactions of azomethine ylides to produce pyrrolidine derivatives has been published. The Diels-Alder cycloaddition of allylidenecyclopropane with a variety of cyclic and acyclic dienophiles provides a pathway to the tricyclic ring system of the Illudin group of natural products.