Towards bis(acylsilanes) and cyclic unsaturated acylsilanes via metathesis: an exploratory study

New acyl(allyl)- and acyl(vinyl)silanes have been synthesized in order to explore cross metathesis or ring-closing metathesis as a new way towards bis(acyl)silanes or unsaturated cyclic acylsilanes, respectively. Metathesis from acylsilanes did not work but their precursors, in particular in benzotriazol series, proved to be good candidates. Two new benzotriazolyl substituted silacyclic compounds (tetrahydrosiline and dihydrosilol) were thus prepared by RCM. Their conversion into the corresponding acylsilane failed. In contrast, the preparation of a bis(acylsilane) bearing the silicon atoms in internal position was achieved by a two-step sequence: cross metathesis of an allyl(dimethylsilyl) benzotriazolyl intermediate-hydrolysis.