Titre : Sulfenic Acid Anions: Emerging Sulfur Nucleophiles for Synthesis and Stereochemistry.
Endroit : Pavillon Roger-Gaudry, salle G-715 à 11 h.
Hôte : Professeur William Lubell.
La conférence sera prononcée (en anglais) par le professeur Adrian Schwan, du Département de chimie de l'University of Guelph.
Résumé : Sulfenic acid anions, or sulfenates, which possess the general structure RSO-M+, are nucleophilic prochiral sulfur species that simultaneously deliver a sulfur and an oxygen to an organic substrate. They are central to a bourgeoning area of study that encompasses organometallic cross couplings and organocatalysis. The Schwan group has previously introduced two methods of generating sulfenate anions and more recently, has demonstrated for the first time, their successful use as prochiral entities upon reaction with homochiral electrophiles. The products obtained are chiral β-substituted, β-amino sulfoxides. One family of those products, the 1-alkenyl β-substituted-b-aminoalkyl sulfoxides has been subjected to a stereoselective cyclization to create E-3,5-disubstituted thiomorpholine-S-oxides, which bear a third stereogenic centre. By contrast, cyclization of the sulfone form gives the Z-isomer. Novel conditions for Ramberg-Backlund desulfurization of these compounds and hydrogenation completes the enantioselective formation of E- or Z-2,4-disubstituted pyrrolidines, known constituents of ant venom.
