A decarboxylative protocol has been
developed toward a range of
carbocycles. The key success is based on the use of a batch of newly
designed cyclic carbonates as substrates that can provide carbon–carbon
zwitterion intermediate under palladium catalysis. The kinetics of
the reactions are controllable toward either strained seven- or thermodynamically
more favored five-membered carbocycles. The release of this chemistry
will shed light on the synthesis of complex and valuable cyclic structures.
Functionalized cyclic organic carbonates and carbamates are frequently used in a number of transition metal-catalyzed decarboxylative reactions for the construction of interesting molecules. These decarboxylative transformations have attracted more and more research attention in recent years mainly due to their advantages of less waste generation and versatile reactivities. On the basis of previous reviews on this hot topic, the present review will focus on the development of transition metal-catalyzed decarboxylative transformations of functionalized cyclic carbonates and carbamates in the last two years.
A propargylic
amination approach toward chiral acyclic α-quaternary
α-amino ketones is described. This Cu-catalyzed procedure could
be performed open to air using commercially available amines as nucleophiles.
The key to success is the use of rationally designed propargylic cyclic
carbonates as substrates, which can generate a Cu-bonded enolate zwitterionic
intermediate upon decarboxylation. This protocol features wide functional
group tolerance and high asymmetric induction, with typical ee value higher than 93%, and thus advances a great step
forward in the challenging synthesis of acyclic chiral α-quaternary
α-amino ketones.
A Pd-catalyzed decarboxylative approach
for the modular synthesis
of highly functionalized pyrroles is presented. This protocol utilizes
readily available cyclic carbonates and amines as reaction partners
and only generates CO2 and H2O as byproducts.
This methodology could be operated at room temperature and open to
air, thus serving as an ideal means for the derivatization of bioactive
compounds. Mechanism investigations suggested that the stereoselective
formation of the (Z)-configured γ-amino ketone
intermediate is crucial for the success of the reaction.
A water-mediated catalytic decarboxylation process toward the formation of polysubstituted furans and (E)-allylic alcohols has been reported. This protocol features wide functional group tolerance, easy operation, and only CO 2 -byproduct generation. These reactions can be performed on a large scale open to air under extremely ambient conditions. A range of control experiments revealed the crucial role of the water for the successful conversions as well as the origin of the chemoselectivity and exclusive stereoselectivity.
A practical and straightforward methodology toward the synthesis of non-fused N-aryl azepane derivatives with diversity is described. These Pd/LA-catalyzed reactions proceed smoothly under extremely mild conditions with ample reaction scope...
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