A dibromocarbene undergoes this reaction, then an alpha elimination, in the Corey-Fuchs mechanism.
Edwin Vedejs upended the once-prevalent Bergelson mechanism for this reaction by showing the NMR spectrum of a pseudo-rotamer intermediate has peaks at -60 ppm, not 10 ppm. The product distribution of this reaction depends on if an intermediate is "stabilized" or just "semi-stabilized." Its intermediate is analogous to the intermediates in the reactions of the Seyferth-Gilbert reagent and Tebbe's reagent. This reaction's intermediate converts between diastereomers at high temperatures due to stereochemical (*) drift. A dibromocarbene undergoes this reaction, then an alpha elimination, in the Corey-Fuchs mechanism. Unusually, the lithium-salt free version of this reaction is under kinetic control to form the more unstable Z-product. Its crucial intermediate is either an erythro zwitterion separated by two carbons, a four-member oxaphosphetane ring, or both. For 10 points, name this classic carbonyl-to-alkene reaction which uses a phosphonium ylide.
Edwin Vedejs upended the once-prevalent Bergelson mechanism for this reaction by showing the NMR spectrum of a pseudo-rotamer intermediate has peaks at -60 ppm, not 10 ppm.
Wittig reaction