The Synthesis and Chemistry of 8‐Substituted Bicyclo[5.1.0]oct‐1(8)‐ene

Abstract 8‐Bromobicyclo[5.1.0]oct‐1(8)‐cne (7), an intermediate for the preparation of 8‐substituted bicyclo[5.1.0]oct‐1(8)‐enes, was synthesized by denomination of 1,8,8‐tribromobicyclo[5.1.0]octane (6). Compound 7 underwent bromo‐lithium exchange followed by nucleophilic substitution reactions to generate bicyclo[5.1.0]oct‐1(8)‐ene (5), 8‐methylbicyclo[5.1.0]oct‐1(8)‐ene (10), and 8‐trimethylsilylbicyclo[5.1.0]oct‐1(8)‐ene (11). The bicyclic cyclopropenes 7, 5, 10, and 11 reacted with cyclopentadiene to form adducts 12, 13, 14, and 15, respectively. All of these Diels‐Alder adducts are endo‐exo isomers (endo‐addition from the view of the cyclopropene and exo‐addition from the view of the cyclooctene).