An Annulation Reaction for the Synthesis of Morpholines, Thiomorpholines, and Piperazines from β‐Heteroatom Amino Compounds and Vinyl Sulfonium Salts

Heterocycling: Diphenyl vinyl sulfonium salt 1 acts first as an electrophile, then a base, and then again as an electrophile in this operationally simple, high yielding, one-pot synthesis of pharmacologically important morpholines, thiomorpholines, and piperazines. Compound 1 is an excellent synthon for the 1,2-ethane dication.