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Easy Access to Enantiomerically Pure Heterocyclic Silicon‐Chiral Phosphonium Cations and the Matched/Mismatched Case of Dihydrogen Release
Author(s) -
Fontaicolò,
EspinosaJalapa Noel Angel,
Seidl Michael,
Bauer Jonathan O.
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202005171
Subject(s) - phosphonium , chemistry , stereocenter , chirality (physics) , protonation , borane , combinatorial chemistry , lewis acids and bases , catalysis , enantioselective synthesis , hydride , chemoselectivity , organic chemistry , ion , hydrogen , chiral symmetry breaking , physics , quantum mechanics , quark , nambu–jona lasinio model
Phosphonium ions are widely used in preparative organic synthesis and catalysis. The provision of new types of cations that contain both functional and chiral information is a major synthetic challenge and can open up new horizons in asymmetric cation‐directed and Lewis acid catalysis. We discovered an efficient methodology towards new Si ‐chiral four‐membered CPSSi* heterocyclic cations. Three synthetic approaches are presented. The stereochemical sequence of anchimerically assisted cation formation with B(C 6 F 5 ) 3 and subsequent hydride addition was fully elucidated and proceeds with excellent preservation of the chiral information at the stereogenic silicon atom. Also the mechanism of dihydrogen release from a protonated hydrosilane was studied in detail by the help of Si ‐centered chirality as stereochemical probe. Chemoselectivity switch (dihydrogen release vs. protodesilylation) can easily be achieved through slight modifications of the solvent. A matched/mismatched case was identified and the intermolecularity of this reaction supported by spectroscopic, kinetic, deuterium‐labeling experiments, and quantum chemical calculations.