The Reactions of 4,5-Dehydrotropone with 4-Phenyloxazols.

Abstract 4,5-Dehydrotropone reacted with 4-phenyl-, 5-methyl-4-phenyl-, and 2,5-dimethyl-4-phenyloxazol to give, involving facile loss of benzonitrile from the corresponding Diels-Alder adducts, furo-[3,4-d]tropone and its 1-methyl and 1,3-dimethyl derivative, respectively. Protonation of furo[3,4-d]-tropones yielded delocalized 6-hydroxy-3-oxaazulenium ions.