Face Selectivity of the Diels‐Alder Additions of 2‐Substituted 5,6‐bis((E)‐chloromethylidene)bicyclo[2.2.2]octanes

The preparation of 5,6‐bis((E)‐chlorommethylidene)bicyclo[2.2.2]oct‐2‐ene (13), 2,3‐bis((E)‐chloromethyl idene)‐5exo,6exo‐ and ‐5endo,6endo‐epoxybicyclo[2.2.2] octane (14 and 15), 5,6‐bis((E)‐chloromethylidene)‐2exo‐ and ‐2endo‐bicyclo[2.2.2] octanol (16 and 17) and 5,6‐bis((E)‐chloromethylidene)‐2‐bicyclo[2.2.2]octanone (18) are described. The face selectivity (endo‐face vs. exo‐face attack onto the exo‐cyclic diene) of their cycloadditions to tetracyanoethylene has been determined in benzene at 20°. It is 78/22, 80/20, 60/40, 68/32, 3/97 and 30/70 for 13, 14, 15, 16, 17 and 18, respectively.