(2003), Azomethine Ylides in Organic Synthesis
21/12/2017 · Azomethine Ylides in..
Cycloaddition reactions are among the most powerful methods for the synthesis of complex compounds. In particular, the development and application of the 1,3-dipolar cycloaddition, an important member of this reaction class, has grown immensely due to its powerful ability to efficiently build various five-membered heterocycles. Azomethine ylides are commonly used as dipoles for the synthesis of the pyrrolidine scaffold, which is an important motif in natural products, pharmaceuticals, and biological probes. The reaction between azomethine ylides and cyclic dipolarophiles allows access to polycyclic products with considerable complexity. The extensive application of the 1,3-dipolar cycloaddition is based on the fact that the desired products can be obtained with high yield in a regio- and stereocontrolled manner. The most attractive feature of the 1,3-dipolar cycloaddition of azomethine ylides is the possibility to generate pyrrolidines with multiple stereocenters in a single step. The development of enantioselective cycloadditions became a subject of intensive and impressive studies in recent years. Among many modes of stereoinduction, the application of chiral metal–ligand complexes has emerged as the most viable option for control of enantioselectivity.
A ylide or ylid (/ ˈ ɪ l ɪ d / or ..
The synthetic usefulness of this step is demonstrated in generating reactive intermediates such as nitrones, iminium cations, α-amino radicals and azomethine ylides depending on the substrates and reaction medium.