Site specificity in 1,3-dipolar cycloadditions to a polycyclic polyene induced by complexation with tricarbonyliron

Treatment of dimethyl tricyclo[4.2.2.0(2,5)] deca-3,7,9-triene-7,8-dicarbox ylate (1) with nonacarbonyldiiron led to dimethyl 7-10-tetrahaptotricyclo[4 .2.2.0(2,5)]deca-3,7,9-triene-7,8-dicarboxylate tricarbonyliron (12). This derivative reacted smoothly with several 1,3-dipoles (nitrones, nitrile oxi des, nitrile imines and diazoalkanes) at the cyclobutene double bond to giv e adducts from which the tricarbonyliron group could be easily removed by o xidative decomplexation with trimethylamine N-oxide. Thus, a formal site sp ecific attack of 1,3-dipoles to 1 was achieved.