Vicinal elimination of trimethylsilyl and benzotriazolyl groups from 2-benzotriazolyl-2-aryl-3- ketopropylsilanes forms, along with the expected 1, 1-disubstituted ethylenes, significant amounts of the corresponding chalcones. A study of this transformation by carbon labeling suggests the intermediate formation of cyclopropanes. Stabilizing/destabilizing (electron- donor/acceptor) para-substituents on the aryl group affect the product distribution of the ...