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Mechanistic Studies on the Pd‐catalyzed Direct CH Arylation of 2‐Substituted Thiophene Derivatives with Arylpalladium Bipyridyl Complexes
Author(s) -
Steinmetz Marc,
Ueda Kirika,
Grimme Stefan,
Yamaguchi Junichiro,
Kirchberg Sylvia,
Itami Kenichiro,
Studer Armido
Publication year - 2012
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201101011
Subject(s) - regioselectivity , thiophene , chemistry , cationic polymerization , electrophile , catalysis , medicinal chemistry , stoichiometry , derivative (finance) , stereochemistry , polymer chemistry , organic chemistry , financial economics , economics
Direct CH phenylation of 2‐ethylthiophene and 2‐chlorothiophene with PhPdI(bipy) complex to form either the corresponding 4‐phenyl or 5‐phenylthiophene derivative is studied under stoichiometric conditions using various Lewis acids as additives. It is shown that reactions occur via the corresponding cationic Pd complex (PhPdbipy + ) and that the counteranion determines the regioselectivity. High‐level DFT calculations reveal that CC bond formation occurs via a carbopalladation pathway and not via electrophilic palladation. These calculations give some indications regarding the regioselectivity of the thiophene arylation .