Generation and reactions of nonstabilized 1,3-dipolar reagents - Unprecedented access to the preparation of "Tailor-made" carbonyl ylides

Unprecedented approach to nonstabilized. carbonyl ylides can be attained by the following three methods: 1) the 1,3-elimination of organosilicon compounds under mild and neutral conditions, 2) the generation from iodomethyl silyl ethers promoted by samarium reagents as a reductant, and 3) the reductive metalation of cr-chloroalkyl alpha'-chloroalkyl ethers by samarium and activated manganese reagents followed by 1,3-elimination of metal halide from the intermediate. The last method is especially attractive for the generation of "Tailor-made" carbonyl ylides bearing not only nonstabilized substituents but also no substituents (the parent carbonyl ylide). Using these novel and synthetically practical carbonyl ylides, it has been elucidated that carbonyl ylides reveals high reactivities toward activated and nonactivated alkenes, alkynes, and a variety of heterodipolarophiles such as compounds including C=O, C=N, C=S, N=N double bonds, and optionally substituted and stereochemically defined tetrahydrofurans, dihydrofurans, dioxolanes, and oxazolidines are conveniently synthesized in a single step.