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

Abstract The preparation of 5,6‐bis(( E )‐chlorommethylidene)bicyclo[2.2.2]oct‐2‐ene ( 13 ), 2,3‐bis(( E )‐chloromethyl idene)‐5 exo,6exo ‐ and ‐5 endo,6endo ‐epoxybicyclo[2.2.2] octane ( 14 and 15 ), 5,6‐bis(( E )‐chloromethylidene)‐2 exo ‐ and ‐2 endo ‐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.