title: Insights into the β-sultam ring formation in the sulfa-Staudinger cycloadditions.
abstract: The reaction of imines with sulfonyl chlorides or even direct sulfenes to form β-sultams is herein named as sulfa-Staudinger cycloaddition. The β-sultam formation is proposed to follow a stepwise mechanism of sulfonylation, deprotonation, and conrotatory ring closure with 2,3-thiazabutadiene-type zwitterionic intermediates as key intermediates. Cyclic (Z)-imines give rise to trans-β-sultams exclusively, suggesting that the intermediates generated from linear (E)-imines undergo a conrotatory ring closure directly to afford cis-β-sultams. Meanwhile, their iminium isomers lead to trans-β-sultams via the conrotatory ring closure.
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Department of Organic Chemistry, Faculty of Science, Beijing University of Chemical Technology , Beijing 100029, People's Republic of China.
authors.forename: Zhanhui
authors.initials: Z
authors.lastname: Yang
authors.forename: Jiaxi
authors.initials: J
authors.lastname: Xu
mesh_terms: D061565:Cycloaddition Reaction; D007097:Imines / Q000737:chemistry*; D013237:Stereoisomerism; D013441:Sulfinic Acids / Q000737:chemistry*; D013449:Sulfonamides / Q000737:chemistry*
chemical_list: D007097:Imines; D013441:Sulfinic Acids; D013449:Sulfonamides; C480101:beta-sultam; C044255:sulfonyl chloride