Compartmentalization of Incompatible Catalytic Transformations for Tandem Catalysis

In
Nature, incompatible catalytic transformations are being carried
out simultaneously through compartmentalization that allows for the
combination of incompatible catalysts in tandem reactions. Herein,
we take the compartmentalization concept to the synthetic realm and
present an approach that allows two incompatible transition metal
catalyzed transformations to proceed in one pot in tandem. The key
is the site isolation of both catalysts through compartmentalization
using a core–shell micellar support in an aqueous environment.
The support is based on amphiphilic triblock copolymers of poly­(2-oxazoline)­s
with orthogonal functional groups on the side chain that can be used
to cross-link covalently the micelle and to conjugate two metal catalysts
in different domains of the micelle. The micelle core and shell provide
different microenvironments for the transformations: Co-catalyzed
hydration of an alkyne proceeds in the hydrophobic core, while the
Rh-catalyzed asymmetric transfer hydrogenation of the intermediate
ketone into a chiral alcohol occurs in the hydrophilic shell.