Cationic Cyclization to Tricyclene Structures

摘要

Various carbocation-mediated cyclizations to tricyclene structure (basically, tricyclo [2,2,1,02,6] heptane skeleton) were carried out, starting from protonated species of either 3-methyl-2,5-norbornadiene-2-carboxylic acid (10) or 3-methylene-5-norbornene-2-carboxylic acids (18 and 19). The resulting products were individually converted to ヰ-iodotricyclene (35), a pivotal intermediate in almost all syntheses of tricyclene terpenes.