Flash thermolysis: multiple sigmatropic rearrangements in ortho-substituted aromatic compounds

A number of o-disubstituted benzenoid substances on flash thermolysis undergo 1,4-elimination of water or alcohols to yield o-quinonoid derivatives. Those products possessing a pentadienyl hydrogen subsequently undergo a 1,5-sigmatropic rearrangement: in many cases the rearrangement product undergoes yet further transformations, such as addition or hydrolysis, and such reactions have been used for their characterization. Included are: the conversion of N-methyl anthranilate esters to o-aminobenzaldehyde; o-(N-methyl)benzyl alcohol and methyl ether to o-toluidine; o-methoxymethylformanilide to o-tolyl isocyanate; and o-carboxymethylformanilide to o-aminobenzaldehyde.