Summary Cobalt (I1) tetraarylporphyrins supported through carboxamide and sulfonamide linkages on aminated macroreticular polystyrene beads cross-linked with divinylbenzene provide an active and inexpensive catalyst for the valence isomerization of quadricyclane (11) to norbornadiene (I). The presence of unreacted pendant amino groups causes some difficulties in the analysis of the system both because of lack of a direct method for ...