D. Armesto et al., A NEW PHOTOCHEMICAL-SYNTHESIS OF CYCLOPROPANECARBOXYLIC ACIDS PRESENTIN PYRETHROIDS BY THE AZA-DI-PI-METHANE REARRANGEMENT, Tetrahedron, 51(33), 1995, pp. 9223-9240
A novel synthetic route to chrysanthemic acid, entylidenmethyl-3,3-dim
ethylcyclopropanecarboxylic acid, fluorenespiro-2,2-dimethylcyclopropa
necarboxylic acid and indenespiro-2,2-dimethylcyclopropanecarboxylic a
cid, all of them present in pyrethroids of known insecticidal activity
, is described. The key step in the synthesis is the aza-di-pi-methane
rearrangement of some 1-aza-1,4,6-trienes and some 1-aza-1,4-dienes,
using tripler sensitization.