One of them is formed in the intermediate stages of the Stevens rearrangement.
One of them is formed in the intermediate stages of the Stevens rearrangement. Dimsyl sodium  generates these compounds in a DMSO solution, and the Corey-Chaykofsky reagent is a sulfonium  variety of them used to prepare epoxides. The best known of these (*) dipolar compounds is probably the phosphonium variety. For 10 points— identify these molecules which help convert an aldehyde or a ketone to an alkene in the Wittig reaction.
One of them is formed in the intermediate stages of the Stevens rearrangement.
ylides