DIELS-ALDER REACTIONS OF 1,2,3,6-TETRAHYDROBENZOCYCLOBUTENE-3,6-DIONES. A NEW SYNTHESIS OF PROPELLANES AND A DIVERGENCE OF SITESELECTIVITY CONTROLLED BY STERIC HINDRANCE

Article abstract of DOI:10.1246/cl.1981.1547

1,2,3,6-Tetrahydrobenzocyclobutene-3,6-diones underwent Diels-Alder reactions most preferably at the internal double bond giving <4.4.2>propellanes unless steric hindrance is not significant.The adducts with cyclic 1,3-dienes were transformed photochemica