Previous studies2p3 have demonstrated the generality of the conversion of 3, 4- polymethylene-2-pyrazolin-5-ones to cycloalkene-l-carboxylic acids in two steps: first by conversion to the 4-halo-3, 4-polymethylene-2-pyrazolin-Bone and then by a ring-opening reaction with aqueous sodium hydroxide. In related work, Taylor's group4 has converted 3, 4- dialkyl-2-pyrazolin-5-ones directly to acyclic allenic esters using thallium (II1) nitrate and ...