Bond
activation and catalysis are central to the development of
a sustainable energy system. Frustrated Lewis Pairs have conceptually
revolutionized the activation of inert chemical bonds. Far less developed
are hybrid systems containing at least one transition metal as part
of the electron-donating/accepting composition. These cooperative
transition metal architectures present advantages over traditional
systems. For instance, they incorporate, to the concept of FLPs, the
movement of electron pairs as typically encountered in the elementary
steps of organometallic catalysis. This Perspective presents arguably
the most relevant and recent progress of a vivid field of research
that aspires to implement cooperative designs in polarized transition
metal systems. Moreover, it provides tools for future developments
and shows that molecular control over bond-making and -breaking processes
can be achieved.
The direct synthesis
of amides and nitriles from readily available
aldehyde precursors provides access to functional groups of major
synthetic utility. To date, most reliable catalytic methods have typically
been optimized to supply one product exclusively. Herein, we describe
an approach centered on an operationally simple iron-based system
that, depending on the reaction conditions, selectively addresses
either the CO or C–H bond of aldehydes. This way, two
divergent reaction pathways can be opened to furnish both products
in high yields and selectivities under mild reaction conditions. The
catalyst system takes advantage of iron’s dual reactivity capable
of acting as (1) a Lewis acid and (2) a nitrene transfer platform
to govern the aldehyde building block. The present transformation
offers a rare control over the selectivity on the basis of the iron
system’s ionic nature. This approach expands the repertoire
of protocols for amide and nitrile synthesis and shows that fine adjustments
of the catalyst system’s molecular environment can supply control
over bond activation processes, thus providing easy access to various
products from primary building blocks.
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