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Selective CH Bond Functionalization of 2‐(2‐Thienyl)pyridine by a Rhodium N‐Heterocyclic Carbene Catalyst
Author(s) -
RubioPérez Laura,
Iglesias Manuel,
Castarlenas Ricardo,
Polo Victor,
PérezTorrente Jesús J.,
Oro Luis A.
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201402507
Subject(s) - chemistry , pyridine , carbene , reductive elimination , alkene , alkyne , thiophene , moiety , catalysis , hydride , reactivity (psychology) , medicinal chemistry , rhodium , catalytic cycle , photochemistry , combinatorial chemistry , organic chemistry , hydrogen , medicine , alternative medicine , pathology
[Rh(μ‐Cl)(H) 2 (IPr)] 2 (IPr=1,3‐bis‐(2,6‐diisopropylphenyl)imidazol‐2‐ylidene) catalyzes the selective functionalization of 2‐(2‐thienyl)pyridine efficiently with a range of alkenes and internal alkynes. A catalytic cycle is proposed on the basis of the identification of key reaction intermediates and the study of their reactivity by NMR spectroscopy. Theoretical calculations at the DFT level support that the reaction proceeds by initial κ 1 N coordination of 2‐(2‐thienyl)pyridine followed by the loss of H 2 to afford the active catalyst. Subsequently, cyclometalation of 2‐(2‐thienyl)pyridine, coordination of the unsaturated substrate (alkyne or alkene) at the vacant position trans to the hydride, and reductive elimination of the thiophene moiety occur. Finally, cyclometalation of the thiophene moiety renders the hydride cis to the unsaturated substrate, which leads to migratory insertion into the RhH bond and subsequent reductive elimination of the functionalized product.