Nucleophilic Organosilicon Intermediates Turned Electrophilic: (Trimethylsilyl)methyl, Trimethylsilyloxy and also 2-Tetrahydropyranyloxy as Terminators of Cycloadditions of Allyl Cations. A Short Route to Dehydrozizaenes (6-Methylenetricyclo[6.2.1.01,5]-undec-9,10-enes) and Related Tricycles and [3.2.1]-Bicycles.

Abstract A range of suitable precursors were synthesized in order to contrast and use Me 3 SiCH 2 -, Me 3 SiO- and THPO-groups as terminators in both inter- and intramolecular cycloadditions of allyl cations to cyclic 1,3-dienes. A variety of crowded bicyclic, tricyclic, and spirofused adducts with [3.2.1]skeletons were obtained. The compounds are of interest, e.g., in perfumery. The work contributes to the development of carbocation-induced cyclization methodology.