Synthesis of 3-Substituted Tricyclo[3.2.1.0~(3,8)]octanes

3-Substituted tricyclo [3.2.1.03,6] octanes (1a-1d) have been synthesized by a highly efficient reaction sequence from bicyclo [2.2.1] hept-5-ene-2-endo-carboxylic acid (2) in a 35% over-all yield. In the regio-and stereo-selective synthetic route, thekey step--construction of the cyclobutane ring--is especially noteworthy owing to itspotential generality for the preparation of other strained ring systems.