Diaryldichlorocarbonyl Ylides Derived from Dichlorocarbene and Aromatic Ketones

Article abstract of DOI:10.1021/jo00159a022

The thermal decomposition of phenyl(bromodichloromethyl)mercury (4) in the presence of benzophenone (2) in dry benzene at 80 degC resulted in α-chlorodiphenylacetyl chloride (6) as the only major initial product together with small amounts of dichlorodiphenylmethane (5) and carbon monoxide.Analogous products were observed from fluorenone (3).Dimethyl acetylenedicarboxylate (15) failed to trap the presumed intermediate dihalocarbonyl ylide from either ketone.Attempts to explain the difference in behavior between dihalocarbonyl ylides derived from benzaldehydes and diaryl ketones suggest that in the latter case a twist in the plane of the ylide caused by endo,endo interactions of a chlorine and an aromatic ring leads to rapid closure to oxirane 11 followed by rearrangement to acid chloride 6.Alternative explanations are also explored.