The structure of thianthrenium biscarbethoxymethylide and the corresponding sulfoxide

Abstract

AbstractThianthrene reacts with one equivalent of diethyl diazomalonate to form the monosulfonium ylide thianthrenium biscarbethoxymethylide. Single crystal X‐ray and 13C‐nmr establish the conformation as pseudoequatorial (e') in both the solid state and solution. The angle of fold between aryl rings is 135.7°, the nearlyplanar malonylide fragment bisecting this angle. The carbonyl oxygen of the endo carbethoxy group is anti to the nonbonding electron pair on sulfur. The methylide carbon resonates at 50 ppm. The aromatic solvent induced shift (ASIS) technique indicates that thianthrene Soxide also is e'.