Norchrysanthemic acid

Norchrysanthemic acid (35) was first synthesized by Staudinger in 1924 [16] as the pyrolytic decomposition product of chrysanthemun dicarboxylic acid (36) (Scheme 6). In the 1970s, Ohno and Elliott independently reported [17] insecticidal norchrysanthemic acid esters and these norchrysanthemic acid esters showed comparable insecticidal activity to the corresponding chrysanthemates (Fig. 3). 

However, further studies were discontinued at that time because they could not find any advantage in developing these norchrysanthemic acid esters due to the increased difficulty in the synthesis of norchrysanthemic acid compared to chrysanthemic acid. 

We directed our attention to norchrysanthemic acid esters because they had a lower molecular mass (—14) and showed comparable insecticidal activity with corresponding chrysanthemates. We synthesized various insecticidal norchrysanthemic acid esters and tested their vapor activity against mosquitoes. 

The acid moiety of metofluthrin is (T/ )-norchrysanthemic acid. In this section we describe the development of synthetic studies of Z-rich norchrysanthemic acid. Aforementioned norchrysanthemic acid was first synthesized by Staudinger in 1924 as the pyrolytic decomposition product of chrysanthemun dicarboxylic... 

Synthesis of (Z)-(lR)-trans-Norchrysanthemic Acid by the Wittig Reaction... 

Hagiya et al. recently reported [20] the new decarboxylation catalyst of chrysanthemum dicarboxylic acid monomethyl ester (46) to give ethyl (Z)-norchrysanthemate (EIZ = 4/96) in 59% yield. This method efficiently gives (Z)-(l R)-lrans-norchrysanthemic acid, but the yield is still moderate and the starting chrysanthemum dicarboxylic acid monomethyl ester is not a commercial product (Scheme 7). 

Scheme 7 Synthesis of Z-norchrysanthemic acid by decarboxylation reaction with Cu20 and quinoline...

Scheme 8 Synthesis of Z-norchrysanthemic acid via the Claisen rearrangement...

There are two asymmetric carbon atoms and E, Z-isomers in norchrysanthemic acid. So, there exist eight stereoisomers. In order to elucidate the structure activity relationship of metofluthrin stereoisomers, we investigated the synthetic pathways of all stereoisomers of norchrysanthemic acid. 

In conclusion, all of the eight stereoisomers of norchrysanthemic acid methyl esters were synthesized in stereoselective manner starting from (1/ )-inmv-chrysanthemic acid or (+)-3-carene. All stereoisomers of metofluthrin were synthesized in our laboratory. Their structure-activity relationship will be published elsewhere. 

In 1924, Staudinger, et al., reported a norchrysanthemic acid as the principal acidic product from the pyrolytic decomposition of chrysanthemum dicarboxylate... 

Figure 3). The first insecticidal derivatives, 6-halo-3,4-methylenedioxy-benzyl esters were reported in 1965 [2], but their insecticidal activities were not described in the paper. In the 1970 s, Ohno [3] and Elliott [4] reported their insecticidal esters. They reported that some norchrysanthemate esters showed comparable insecticidal activity to the corresponding chrysanthemates. However, further studies were discontinued at that time because they could not find any justification to develop these norchrysanthemic acid esters due to the difficulty of synthesizing norchrysanthemic acid. Despite this, we directed our attention to the norchrysanthemic acid esters because they had a lower molecular... 

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