A New Photochemical Synthesis of Cyclopropanecarboxylic Acids Present in Pyrethroids by the Aza-di-?-methane Rearrangement

Article abstract of DOI:10.1016/0040-4020(95)00527-F

A novel synthetic route to chrysanthemic acid, 2-cyclopentylidenmethyl-3,3-dimethylcyclopropanecarboxylic acid, fluorenespiro-2,2-dimethylcyclopropanecarboxylic acid and indenespiro-2,2-dimethylcyclpropanecarboxylic acid, all of them present in pyrethroids of known insecticidal activity, is described.The key step in the synthesis is the aza-di-?-methane rearrangement of some 1-aza-1,4,6-trienes and some 1-aza-1,4-dienes, using triplet sensitization.