THE CHEMISTRY OF COMPOUNDS DERIVED BY MICROBIAL OXIDATION OF BENZENE AND DERIVATIVES - CYCLOADDITIONS INVOLVING 1,2-ISOPROPYLIDENEDIOXYCYCLOHEXADIENES

Various cycloadditions involving the cyclohexadiene derivatives 7-10 have been investigated. Diels-Alder reactions involving dimethyl acetylenedicarboxylate, nitrosobenzene and N-ethylmaleimide gave the adducts 11-14, 16-17 and 18-23 respectively. Hydrolysis of the tricyclic compound 11 with pig liver esterase provided the optically active monoester 15. Tropone, and three carbenes reacted with the diene 7 to give the polycyclic compounds 24 and 29, 31 and 33 as expected. The structure of the adduct 24 was elucidated by X-ray crystallography. The ester 32 was converted into the lactone 36 by way of an oxa-Cope rearrangement of the aldehyde 34. The dienes 7 and 8 reacted with diphenylketene in an unexpected fashion giving the enol ethers 27 and 28 as well as the expected [2 + 2] cycloaddition products 25 and 26.