Palladium-Catalyzed Cross-Coupling of Organosilicon
Compounds
It is axiomatic that the development of new, selective and
general carbon-carbon bond forming reactions is central to
the mission of organic synthesis. Over the past 30 years, the
transition metal catalyzed cross-coupling of organometallic
donors with organic acceptors has revolutionized the construction
of bonds between unsaturated centers. The impact of this process
across the entire chemical landscape is breathtaking and reflected
in the number of publications (>7700) appearing on this
topic since its formal birth in 1972. Further, the doubling
in publication frequency from 1996 (285) to 2000 (554) and
again to 2004 (1105) provides compelling testimony to the vigor
and outlook for the field.
We have recently discovered that organosilanols are viable
partners in palladium-catalyzed cross-coupling reactions under
activation by both fluoride and non-fluoride reagents. This
discovery has opened a new dimension for the application of
silicon-based, carbon-carbon bond forming processes. This research
program features advances in the methodological extension of
this reaction including the construction of silanol substrates,
the scope of basic activators, and the diversification of transferable
groups (TG) attached to silicon. A number of powerful constructive
processes have been parlayed with cross-coupling to create
versatile transformations (hydrosilylation, silylformylation,
ring closing metathesis, enyne metathesis, silylcarbocyclization,
dipolar cycloaddition). We have engineered sets of reaction
conditions that allow for cross-coupling in many structural
settings which were heretofore not amenable to palladium catalyzed
bond forming processes. We have dramatically expanded the scope
of substrates (alkenyl, alkynyl, aryl, heteroaryl) that engage
in the coupling. A particularly important application is found
in the ability to effect cross-coupling of heterocyclic silanols
under mild conditions. In addition, kinetic, natural abundance
isotope and crystallographic studies have confirmed the operation
of a new mechanistic paradigm for silanol-based coupling reactions.
The synthetic utility of the silicon-based, cross-coupling
process has been highlighted in the total syntheses of a 9-membered
ring ether, (+)-brasilenyne and a C-aryl glycoside, papulacandin
D.
Read the most recent reviews:
203, 207, 225, Chapter
7
Cross-Coupling Reactions of Organosilanols
Structural Diversity in Silicon-Based Cross-Coupling
Kinetics and Mechanism of Silicon-Based Cross-Coupling
Reactions
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