Cycloadditions of Donor–Acceptor Cyclopropanes and ‐butanes using S=N‐Containing Reagents: Access to Cyclic Sulfinamides, Sulfonamides, and Sulfinamidines

We present (3+2)‐ and (4+2)‐cycloadditions of donor–acceptor (D–A) cyclopropanes and cyclobutanes with N‐sulfinylamines and a sulfur diimide, along with a one‐pot, two‐step strategy for the formal insertion of HNSO2 into D–A cyclopropanes. These are rare examples of cycloadditions with D–A cyclopropanes and cyclobutanes whereby the 2π component consists of two different heteroatoms, thus leading to five‐ and six‐membered rings containing adjacent heteroatoms. By employing (3+2)‐ and (4+2)‐cycloadditions of donor–acceptor (D–A) cyclopropanes and cyclobutanes with N‐sulfinylamines and sulfur diimides, a variety of isothiazolidines and thiazinanes were synthesized. Use of a sulfinylamine bearing a leaving group, followed by oxidation, led to formal insertion of HNSO2 providing γ‐sultams with no N‐substitution.