Diisophorone and Related Compounds. Part 18 Ring Contraction in Diisophorone by the Favorski Reaction

Article abstract of DOI:10.1007/BF00810642

The action of strong alkalis or alkoxides on 4,8-dibromo-1-carboxydiisophor-2(7)-en-3-one produces 1,3-dicarboxyneodiisophora-2,7-diene (or its esters) by a ring-contraction of the Favorski-type; the products are derivatives of tricyclo<6.3.1.0^2,6>dodecane.Hydriodic acid converts the dienedioic acid by partial saturation of the conjugated 2,7-diene system into the 2(7)-mono-olefine dioic acid; the carboxyl groups of both series of compounds undergo esterification, anhydride formation and reduction in the normal manner.The 13C nmr spectra of the novel ring-contracted compounds are interpreted, chiefly by reference to those of their diisophorone-precursors, as are their fragmentation patterns under electron impact. - Keywords: Diisophorone, Favorski ring contraction thereof; "Neodiisophorones"; Tricyclo<6,3,1,0^2,6>dodecanes; 4,8-Methano-1H-cyclopentacyclooctenes