Regioselective Synthesis of Heteroatom‐Functionalized Cyclobutene‐triflones and Cyclobutenones

Abstract The controlled metal‐free synthesis of a vast variety of heteroatom‐containing cyclobutene‐triflones [bis(trifluoromethylsulfonyl)cyclobutenes] and cyclobutenones has been developed starting from heteroatom‐substituted alkynes and a pyridinium salt (a latent Tf 2 C=CH 2 source). This powerful methodology, involving cyclization reactions, allows for the selective preparation of oxygen‐, nitrogen‐, bromine‐, chlorine‐, iodine‐, sulfur‐, selenium‐, tellurium‐, phosphorus‐, and silicon‐functionalized cyclobutene derivatives. magnified image