REACTIVE INTERMEDIATES FROM N-AZIRIDINYLIMINES

N-Aziridinylimines are readily obtained from carbonyl compounds and 1- aminoaziridines, of which the 2-phenyl and trans-2,3-diphenylaziridine derivatives are the most popular. Diazo compounds are formed upon the rmolysis or photolysis of N-aziridinylimines, with elimination of alke nes. The diazo compounds can be trapped by intramolecular addition to alkenes, but otherwise decompose as they are formed, giving rise to ca rbenes and products derived therefrom. The transformation R2CO --> R2C N2 --> R2C is most often achieved with the anions (salts) of arenesulf onylhydrazones. However, the non-ionic and weakly basic N-aziridinylim ines have the advantage that they are compatible with nonpolar solvent s and with a wide range of substituents. These properties were exploit ed in the fragmentations of alpha,beta-epoxyketones (--> alkynones) an d alpha,beta-epoxyaldehydes (--> beta-hydroxyvinylidenes --> cyclopent enols) as well as in the syntheses of unsaturated nitriles, silanes, a nd ethers. Laser flash photolysis of N-aziridinylimines in fluorinated alcohols was used to demonstrate the protonation of carbenes and to m easure absolute reaction rates of carbocations. The Shapiro reaction o f N-aziridinylimines, performed with catalytic amounts of R2NLi, was f ound to produce alkenes with excellent regio-and stereoselectivity. As radical accepters, N-aziridinylimines are superior to alkenes. On thi s basis, selective (tandem) cyclizations were designed for the synthes is of natural products.