Investigations of a New and Improved Precataylst for Palladium Catalyzed Cross Coupling Reactions
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Authors
Fraser, Andrew
Date
2013-07-02
Type
thesis
Language
eng
Keyword
Catalysis , Palladium , Cross-Coupling , Organometallic Chemistry
Alternative Title
Abstract
Little attention has been given to the formation of the putative PdL2
species required for Pd-catalyzed cross-coupling reactions. Active species are
generally difficult to store due to air-sensitivity and are therefore formed in situ at
unknown rates and in unknown yields via a variety of palladium precatalysts.
Commonly employed Pd(0) and Pd(II) precatalysts are often relatively ineffective
because they generate only low concentrations of the bis(phosphine) species
PdL2 under most reaction conditions. This thesis describes the use of the easily
synthesized and easily handled Pd(η3-1-Ph-C3H4)(η5-C5H5) (I) as a superior
precursor than any other documented system for the in situ formation of PdL2.
Rapid and quantitative formation of active catalyst solutions allow us to
demonstrate that I is also the best precatalyst known for PdL2-catalyzed crosscoupling
reactions. We discuss the Suzuki-Miyaura reaction of 4-bromoanisole
with phenylboronic acid and demonstrate that, under mild reaction conditions,
higher initial rates and higher conversions with I can be obtained compared with
other common precatalysts (Pd(OAc)2, Pd(PPh3)4, Pd2dba3, etc.) containing a
variety of phosphine ligands. This methodology has also been extended to other
cross-coupling reactions, as we demonstrate that higher initial rates and higher
conversions with I can be obtained for a variety of Mizoroki-Heck arylations and
Buchwald-Hartwig aminations.
Description
Thesis (Ph.D, Chemistry) -- Queen's University, 2013-06-25 11:53:06.75
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