Cucurbituril Adamantanediazirine Complexes and Consequential Carbene Chemistry

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. 1H 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.