Enantioselective Synthesis of N,S‐Acetals by an Oxidative Pummerer‐Type Transformation using Phase‐Transfer Catalysis |
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| Authors: | Dr Souvagya Biswas Dr Koji Kubota Dr Manuel Orlandi Mathias Turberg Dr Dillon H Miles Prof?Dr Matthew S Sigman Prof?Dr F Dean Toste |
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| Affiliation: | 1. Department of Chemistry, University of California, Berkeley, CA, USA;2. Department of Chemistry, University of Utah, Salt Lake City, UT, USA |
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| Abstract: | Reported is the first enantioselective oxidative Pummerer‐type transformation using phase‐transfer catalysis to deliver enantioenriched sulfur‐bearing heterocycles. This reaction includes the direct oxidation of sulfides to a thionium intermediate, followed by an asymmetric intramolecular nucleophilic addition to form 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 calculations, highlight the existence of a set of weak noncovalent interactions between the catalyst and substrate that govern the enantioselectivity of the reaction. |
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| Keywords: | acetals chiral anions organocatalysis phase-transfer catalysis sulfur |
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