Unambiguous detection of 2,4,6-cycloheptatrien-1-ol by NMR spectroscopy and trapping with phenyltriazolinedione

For the first time, the title alcohol was unambiguously detected as a transient intermediate leading to ditropylether () in a cation–anion reaction between the tropylium ion () and hydroxide ion in an aqueous solution by NMR spectroscopy. It was also found that gives as a transient product in acid-catalyzed disproportionation of into a mixture of tropone () and 1,3,5-cycloheptatriene () in chloroform containing water. Furthermore the existence of in the latter reaction was confirmed by trapping with 4-phenyl-1,2,4-triazoline-3,5-dione to afford the [4+2]cycloadduct of the norcaradiene form of .