Unusual cross-ring SN2 reactions of [M-H]⁻ ions of methoxyacetanilides

Abstract

<jats:title>Abstract</jats:title><jats:p>Deprotonated <jats:italic>o, m</jats:italic>‐, and <jats:italic>p</jats:italic>‐methoxyacetanilide show pronounced peaks in their collision‐induced tandem mass spectra (MS/MS) produced by losses of the elements of C<jats:sub>2</jats:sub>H<jats:sub>6</jats:sub>. It is proposed that this reaction is a ‘cross‐ring’ internal S<jats:sub>N</jats:sub>2 reaction involving an incipient methyl anion. For example, <jats:italic>p</jats:italic>‐CH<jats:sub>3</jats:sub>OC<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub><jats:sup>−</jats:sup>COCH<jats:sub>3</jats:sub>→ [(<jats:italic>p</jats:italic>‐CH<jats:sub>3</jats:sub>OC<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub>NCO)CH<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-stack-1.gif" xlink:title="urn:x-wiley:09514198:media:RCM1290090214:tex2gif-stack-1" />]→<jats:sup>−</jats:sup>OC<jats:sub>6</jats:sub>H<jats:sub>4</jats:sub>NCO+C<jats:sub>2</jats:sub>H<jats:sub>6</jats:sub>.</jats:p>