W0089

A Novel Rearrangement in Silyl-Protected Ortho-Bromophenyl Arylsydnone . David A. Grossie, Douglas M. Krein, and Kenneth Turnbull, Department of Chemistry, Wright State University, Dayton, Ohio 45435

Sydnones are, in most cases, extremely stable crystalline compounds that exhibit a distinct polarity. The five-membered heterocyclic ring is subject to electrophilic substitution at the C-4 position. Only with a strongly activating group present will the 3-aryl group compete effectively for the electrophile, due to the considerable partial positive change at the 3-position of the sydnone ring. Accordingly, it is of interest to explore other avenues to arylsubstituted sydnones. Herein, we report on attempts to react selectively at the ortho position, leading to an interesting 1,5 silyl shift, as shown below.

The precursors and products involving different silyl protecting agents have been examined by single-crystal X-ray diffraction and molecular mechanics in an attempt to understand the mechanism behind this rearrangement.