1, 3-butadiene, 6 2, 3-divinyl-l, 3-butadiene'and bis-(l, &butadienyl) methyl has been prepared in this laboratory. An interesting extension of this series is the cyclic bisdiene, l12, 4, 5-tetramethylenecyclohexane (I). Since several articles in this series have illustrated a method for the conversion of carboxyl groups to exocyclic methylene groups, it appeared that pyromellitic acid would be a convenient starting material. When the project was ...