Enantioselective Synthesis ofN,S‐Acetals by an Oxidative Pummerer‐Type Transformation using Phase‐Transfer Catalysis

Abstract

We report the first enantioselective oxidative Pummerer-type transformation using anionic phase-transfer catalysis, resulting in the formation of enantioenriched sulfur bearing heterocycles. This reaction includes the direct oxidation of sulfides to the thionium intermediate, followed by an asymmetric intramolecular nucleophilic addition to form the chiral cyclic N,S-acetals with moderate to high enantioselectivites. Deuterium labelling experiments were performed to identify the stereodiscrimination step of this process. Further analysis of the reaction transition states by means of multidimensional correlations and DFT computations highlight the existence of a set of weak noncovalent interactions between the catalyst and substrate that governed the enantioselectivity of the reaction.

Access to P-chiral phosphine oxides by enantioselective allylic alkylation of bisphenols

“…Recently, Sigman and coworkers utilized multivariate linear regression (MLR) models to effectively predict the experimental reaction outcome based on both experimentally derived and calculated physical organic molecular descriptors 15. Inspired by their work and our previous related study,12 we explored the factors that govern the stereoselectivity.…”

Enantioselective fluorination of homoallylic alcohols enabled by the tuning of non-covalent interactions

“… 12 , 18 , 36 This method provides a direct analysis tool that enables data driven hypotheses of weak interactions likely involved in the stereochemistry determining step. 12 , 37 Additionally, this approach allows for a union of the knowledge gained from multidimensional, experimentally-derived statistical analysis and TS modeling. Since π-stacking and/or CH–π interactions are likely at play between the BA and PA in this reaction manifold, we computed T E π and T D π parameters, according to the protocol previously described, for several BAs by using benzene as a probe to represent both types of interactions.…”

Erich‐Hückel‐Preis: H.‐J. Werner / Hermann‐Staudinger‐Preis: B. Voit / Alfred‐Stock‐Gedächtnispreis: C. Limberg / Janssen Prize for Creativity in Organic Synthesis: F. D. Toste / EurJIC und EurJOC im 20. Jahrgang

“…Ausgezeichnet wurde Toste für seine Arbeiten über homogene Gold‐Katalyse. Er berichtete in ChemCatChem über Katalysatorentwicklung und Kinetik der Aceton‐Butanol‐Ethanol‐Kondensation und in der Angewandten Chemie über eine enantioselektive oxidative Pummerer‐Transformation …”