Isobenzofuran (IBF) precursor characterization using IR, NMR, X-ray and thermogravimetric analysis

Article abstract of DOI:10.1016/S0022-2860(98)00324-X

The Diels-Alder (DA) addition product of epoxynaphthalene with tetraphenylcyclopentadienone serves as a precursor for isobenzofuran (IBF), one of the most reactive dienes known. A detailed investigation on the DA reaction of epoxynaphthalene with tetraphenylcyclopentadienone shows, that in addition to the main, commonly described DA product [Fieser and Haddadin, J. Am. Chem Soc. 86 (1964) 208; Fieser and Hadddin, Can. J. Chem. 43 (1965) 1599], another stereoisomer by-product is formed. The two isomers are compared with respect to their thermal and spectroscopic properties. Spectroscopic investigations show that Fieser's assumed exo,exo-configuration for the main product is indead an exo,endo-configuration. The by-product turns out to be the exo,exo-stereoisomer.