Cucurbituril Adamantanediazirine
Complexes and Consequential
Carbene Chemistry
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Abstract
Adamantanediazirines, precursors of adamantanylidenes,
form 1:1
complexes (guest to host) with cucurbit[7]uril and cucurbit[8]uril
and a 3:1 complex with a Pd nanocage in water. <sup>1</sup>H NMR spectra
suggested that these complexes are stable in water on the NMR time
scale. While photolysis of adamantanediazirines in water gave mainly
adamantanone and adamantanol via adamantanylidene as intermediate,
the 1:1 complexes of adamantanediazirine with cucurbiturils gave intramolecular
C–H insertion products of adamantanylidene in >90% yield.
The
study establishes that significant control of carbene reactivity can
be achieved when the precursor is encapsulated within a tight inert
cavity. While the general characteristics of molecular containers
can be understood on the basis of concepts such as “confinement”
and “weak interactions”, each one is unique and deserves
careful scrutiny