3-(2-Bromophenyl)-4-(triisopropylsilyl)sydnone

Sydnones are, in most cases, extremely stable crystalline compounds that exhibit a distinct polarity. The five-membered heterocyclic ring that characterizes a sydnone is subject to electrophilic substitution. Only with a strongly activating group present will an attached aryl group compete effectively for the electrophile, due to the considerable partial positive change at the quaternary N atom of the sydnone ring. The title compound, C17H25BrN2O2 Si, is of interest due to an intramolecular shift of the silyl-protecting group that occurs between the syndone ring and the aryl ring when treated with n-butyllithium. This was observed while attempting to replace the aryl bromine. With a curiosity into a rationale for this shift, we have examined a series of precursors, this being the first.