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Direct Access to π‐Extended Phosphindolium Salts by Simple Proton‐Induced Cyclization of ( o ‐Alkynylphenyl)phosphanes
Author(s) -
Arndt Sebastian,
Hansmann Max M.,
Rominger Frank,
Rudolph Matthias,
Hashmi A. Stephen K.
Publication year - 2017
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.201700889
Subject(s) - protonation , phosphonium , exergonic reaction , moiety , chemistry , fluorescence , photochemistry , alkyne , proton , combinatorial chemistry , computational chemistry , organic chemistry , ion , catalysis , physics , quantum mechanics
A detailed synthetic and mechanistic study for the synthesis of phosphindolium salts from easy accessible ( o ‐alkynylphenyl)phosphanes is reported. Mechanistic investigation indicates a fast protonation at phosphorus as evidenced by the isolation of the phosphonium intermediate, followed by a protophosphonylation reaction across the alkyne moiety. DFT calculations support our mechanistic proposal and indicate a reaction highly exergonic compared to our recently reported phosphinoauration. Photophysical measurements recorded fluorescence quantum yields up to 97 % in solution for the phosphindolium core and fluorescence was observed in the solid state.