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Metal‐to‐Ligand Alkyl Migration Inducing Carbon–Sulfur Bond Cleavage in Dialkyl Yttrium Complexes Supported by Thiazole‐Containing Amidopyridinate Ligands: Synthesis, Characterization, and Catalytic Activity in the Intramolecular Hydroamination Reaction
Author(s) -
Lyubov Dmitry M.,
Luconi Lapo,
Rossin Andrea,
Tuci Giulia,
Cherkasov Anton V.,
Fukin Georgy K.,
Giambastiani Giuliano,
Trifonov Alexander A.
Publication year - 2014
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.201303853
Subject(s) - hydroamination , chemistry , thiazole , benzothiazole , medicinal chemistry , ligand (biochemistry) , intramolecular force , catalysis , alkyl , homoleptic , stereochemistry , metal , organic chemistry , biochemistry , receptor
Neutral Y III dialkyl complexes supported by tridentate N − ,N,N monoanionic methylthiazole– or benzothiazole–amidopyridinate ligands have been prepared and completely characterized. Studies on their stability in solution revealed progressive rearrangement of the coordination sphere in the benzothiazole‐containing system through an unprecedented metal‐to‐ligand alkyl migration and subsequent thiazole ring opening. Attempts to synthesize hydrido species from the dialkyl precursor led to the generation of a dimeric yttrium species stabilized by a trianionic N − ,N,N − ,S − ligand as the result of metal‐to‐ligand hydride migration with chemoselective thiazole ring opening and subsequent dimerization through intermolecular addition of the residual YH group to the imino fragment of a second equivalent of the ring‐opened intermediate. DFT calculations were used to elucidate the thermodynamics and kinetics of the process, in support of the experimental evidence. Finally, all isolated yttrium complexes, especially their cationic forms prepared by activation with the Lewis acid Ph 3 C + [B(C 6 F 5 ) 4 ] − , were found to be good candidate catalysts for intramolecular hydroamination/cyclization reactions. Their catalytic performance with a number of primary and secondary amino alkenes was assessed.