Unexpected reactions of Grignard reagents with selected β-carboalkoxy substituted sulfinate esters

Abstract

A series of six-membered rings bearing cis oriented vicinal carboxylate and sulfinate esters were treated with Grignard reagents with the intention of transforming them to ␤-carboalkoxy substituted sulfoxides. The expected outcome did not transpire and instead the substrates demonstrated the capacity to accept 3 equiv. of organometallic agent in an uncontrollable manner. As such, the substrates possessing eclipsing carboxylate and sulfinate esters accepted two organic ligands at the carboxylate functionality and one at the sulfinyl group. When isomer mixtures of sterically encumbered sulfinate esters were reacted, a single sulfoxide stereochemistry resulted. A mechanism involving the intermediacy of a sulfurane is proposed to account for the experimental observations. Résumé : Une série de cycles à six membres portant des esters carboxyliques et sulfiniques vicinaux ont été traités avec des réactifs de Grignard dans le but de les transformer en ␤-carboalkoxy sulfoxydes substitués. Le résultat espéré n'a pas été obtenu et, au lieu de cela, les substrats ont montré une capacité à accepter trois équivalents d'agent organométallique de manière incontrôlable. En tant que tels, les substrats portant des esters carboxyliques et sulfiniques en position éclipsante ont accepté deux ligands organiques au niveau de la fonction carboxylate et un au niveau du groupe sulfinyl. La réaction de mélanges isomériques d'esters sulfiniques stériquement encombrés a débouché sur une seule stéréochimie du sulfoxyde. Un mécanisme impliquant l'intermédiaire d'un sulfurane est proposé, qui permet d'expliquer les observations expérimentales. [Traduit par la Rédaction]Mots-clés : réactif de Grignard, ester sulfinique, sulfoxyde, réaction d'addition, sulfurane.

Diastereoisomerically Pure, (S)-O-1,2-O-isopropyli dene-(5-O-α-d-glucofuranosyl) t-butanesulfinate: Synthesis, Crystal Structure, Absolute Configuration and Reactivity

“…Racemic and optically active diastereoisomeric and/or enantiomeric sulfinic esters played a very important role in the development of sulfur chemistry and especially sulfur stereochemistry [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Preparation of diastereoisomeric O-menthyl p-toluenesulfinates 2a/3a by reacting p-toluenesulfinyl chloride 1a with (-)-(1R,3S,5R)-menthol in the presence of pyridine (Scheme 1) [16], confirmed for the first time stereogenity of a sulfinyl sulfur atom and its optical stability at room temperature [2,3].…”

Looking back on 90 years of the Canadian Journal of Chemistry

“…The inaugural award celebrated the work of the Schwan group (University of Guelph) that identified unexpected outcomes upon treating selected beta-carboalkoxy substituted sulfonate esters with Grignard reagents. 8 This initiative has attracted media attention to the journal. For example, the work by K. Starosta and coworkers (Simon Frasier University) titled "Fukushima-derived radioactivity measurements in Pacific salmon and soil samples collected in British Columbia" was highlighted by Global News and Radio Canada International.…”