This review describes the gold-catalyzed
reactions of specially
activated alkynes, allenes, and alkenes. Such species are characterized
by the presence of either electron-donating or electron-withdrawing
groups as substituents of the carbon π-system. They are intrinsically
polarized, and when compared to their nonspecially activated counterparts
can therefore be involved in gold-catalyzed transformations featuring
increased regio-, stereo-, and chemoselectivities. The chemistry of
specially activated carbon π-systems under homogeneous gold
catalysis is extremely rich and varied. The reactivity observed with
nonspecially activated unsaturated systems can often be transposed
to specially activated ones without loss of efficiency. However, specially
activated carbon π-systems also exhibit specific reactivities
that cannot be attained with regular substrates. In this family of
carbon π-systems, ynamides and their analogs, along with alkynyl
carbonyl derivatives, are the classes of substrates that have retained
the most attention. This review provides an overview of the chemistry
developed with all classes of specially activated carbon π-systems
by discussing their general and specific reactivities, presenting
and commenting on their gold-catalyzed transformations as well as
their applications.
Rh-catalyzed one-step reductive amidation of aldehydes has been developed. The protocol does not require an external hydrogen source and employs carbon monoxide as a deoxygenative agent. The direction of the reaction can be altered simply by changing the solvent: reaction in THF leads to amides, whereas methanol favors formation of tertiary amines.
The confinement of a catalytic site is an efficient strategy to control a reaction and modulate its selectivity. In the present work, a new class of structurally simple and easily accessible bulky tri-(ortho-biaryl)phosphine ligands were accessed, and their gold(I) complexes synthesized. Their X-ray diffraction analysis and the comparative evaluation of their V Bur % and G steric parameters against a series of gold complexes commonly employed in catalysis demonstrated their confined nature. Despite their notable steric congestion, these complexes exhibited remarkable catalytic activities and unusual selectivities, both in nature and level, that make them unique in the field of synthetic homogeneous gold catalysis.
Tertiary amines represent a key class of organic molecules with multiple industrial, synthetic, and analytical applications. The focus of this review is on different approaches towards the synthesis of the C 3 and C 3V symmetrical tertiary amines. Generally, symmetrical tertiary amines can be prepared
Development of novel, sustainable catalytic methodologies to provide access to amines represents a goal of fundamental importance. Herein we describe a systematic study for the construction of a variety of amines catalyzed by a well-defined homogeneous iridium complex using carbon monoxide as a reducing agent. The methodology was shown to be compatible with functional groups prone to reduction by hydrogen or complex hydrides.
A catalytic reaction between aldehydes and primary amides that leads to N‐alkylated amides was investigated. The developed protocol employs carbon monoxide as a deoxygenative agent and, therefore, avoids the use of an external hydrogen source. Cyclopentadienyl ruthenium complexes provided excellent catalytic efficiency and could be used with loadings as low as 0.5–1 mol‐%. A representative number of secondary amides were successfully prepared in yields of 70–84 %.
A new class of anthracene–metal complexes with central ring coordination was tested in catalysis. A simple and efficient protocol for reductive amination without an external hydrogen source has been developed.
The confinement of a catalytic site is an efficient strategy to control a reaction and modulate its selectivity. In the present work, a new class of structurally simple and easily accessible bulky tri-(ortho-biaryl)phosphine ligands were accessed, and their gold(I) complexes synthesized. Their X-ray diffraction analysis and the comparative evaluation of their V Bur % and G steric parameters against a series of gold complexes commonly employed in catalysis demonstrated their confined nature. Despite their notable steric congestion, these complexes exhibited remarkable catalytic activities and unusual selectivities, both in nature and level, that make them unique in the field of synthetic homogeneous gold catalysis.
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