Pyrethrin I is one of the two pyrethrins, natural organic compounds with potent insecticidal activity. It is an ester of (+)- trans- chrysanthemic acid with ( S)-( Z)- pyrethrolone.
Total synthesis [ edit ]
The synthesis of pyrethrin I involves the esterification of (+)-
trans-chrysanthemic acid with (S)-(Z)-pyrethrolone. One synthetic method for each of these is shown in the images below. Sobti and Dev of the Malti-Chem Research Centre in Nadesari, vadodara, India published this method for chrysanthemic acid in 1974. The starting material for the synthesis uses commercially available (+)-3α, 4α-epoxycarane ( 1). A lactone is eventually formed and the ring is opened by the use of a Grignard reagent to give (+)-trans-chrysanthemic acid. The preparation of ( [1 ] S)-pyrethrolone is essentially a 2 step synthesis. The starting material (S)-4-hydroxy-3-methyl-2-(2-propynyl)-2-cyclopenten-1-one ( 7) is also commercially available as the alcohol moiety of ETOC ©. Tetrakis(triphenylphosphine)palladium(0), copper(I) iodide, triethylamine, and vinyl bromide are added to ( 7) to add two more carbons and form ( 8). The final step is the addition of an activated zinc compound to reduce the triple carbon bond to form the cis product, ( S)-pyrethrolone ( 9). Although no journal articles specify the combining of the alcohol and acid moieties of pyrethrin I, they could be combined through an esterification process to form the wanted product. [2 ]
Synthesis of the acid moiety [ edit ]
Synthesis of the alcohol moiety [ edit ]
References [ edit ]
^ Sobti, R., Dev, S. (1974). "(+)-TRANS-CHRYSANTHEMIC ACID FROM (+)-Δ 3-Carene". Tetrahedron 30 (16): 2927–2929. doi: 10.1016/S0040-4020(01)97467-8.
^ Matsuo, N., Takagaki, T., Watanabe, K., Ohno, N. (1993). "The First Practical Synthesis of (S)-Pyrethrolone, an Alcohol Moiety of Natural Pyrethrins I and II". Biosci. Biotech. Biochem. 57 (4): 693–694. doi: 10.1271/bbb.57.693.