Tungsten-Mediated Selective Ring Opening of Vinylcyclopropanes

The
complexes TpW­(NO)­(PMe3)­(L), where L = 2H-phenol, 2H-p-cresol, 2H-5,6,7,8-tetrahydro-2-naphthol, 2H-N,N-dimethylanilinium were cyclopropanated
using Simmons–Smith conditions. Cyclopropanated derivatives
of 2H-N,N-dimethylanilinium were
selectively ring-opened with HOTf/MeCN to form allylic species, which
could be coupled with various nucleophiles. The nucleophilic addition
occurs anti to the metal fragment, as determined
by X-ray crystallography. Moreover, the cyclopropane ring opening
occurs regioselectively, owing to the stabilization of the allylic
cation by the metal fragment. The resulting ligands can, in some cases,
be removed from the metal by oxidative decomplexation using ceric
ammonium nitrate (CAN).