Four newexo- double pyrazolines3–5have been prepared from norbornadiene and dimethyl phenyldiazomethylphosphonate; their structures have been proven by nmr spectroscopy. There is a strong predominance of the isomers with the two aryl groupssynto the bridge. When the two aryl groups were different no electronic interaction between them could be detected by uv spectroscopy. Direct photolysis of the double pyrazolines leads to the corresponding double cyclopropanes with retention of configuration.