Chrysanthemic acid

Chrysanthemic acid is an organic compound that is related to a variety of natural and synthetic insecticides. It is related to the pyrethrin I and II, as well as the pyrethroids. One of the four stereoisomers, (1R,3R)- or (+)-trans-chrysanthemic acid (pictured), is the acid part of the ester pyrethrin I, which occurs naturally in the seed cases of Chrysanthemum cinerariaefolium. Many synthetic pyrethroids, for example the allethrins, are esters of all four stereoisomers.^[1] Staudinger and Ružička named chrysanthemic acid in 1924.^[2]

Chrysanthemic acid

(1R,3R)- or (+)-trans-chrysanthemic acid
Names
IUPAC name 2,2-Dimethyl-3-(2-methylprop-1-enyl)cyclopropane-1-carboxylic acid
Identifiers
CAS Number	4638-92-0 (1R,3R) or (+)-trans Y 2259-14-5 (1S,3S) or (−)-trans Y 26771-11-9 (1R,3S) or (+)-cis Y 26771-06-2 (1S,3R) or (−)-cis Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL1437285
ChemSpider	15876 (+)-trans 19543 (−)-cis
ECHA InfoCard	100.022.788
PubChem CID	16747 (1R,3R) or (+)-trans 33607 (1S,3S) or (−)-trans 33606 (1R,3S) or (+)-cis 20755 (1S,3R) or (−)-cis
UNII	23FP207VLY (1R,3R) or (+)-trans Y 75957WZ15Y (1S,3S) or (−)-trans Y 5P7V8620AM (1R,3S) or (+)-cis Y TFK3B71TRY (1S,3R) or (−)-cis Y
CompTox Dashboard (EPA)	DTXSID101033188 DTXSID60883558, DTXSID101033188
InChI InChI=1S/C10H16O2/c1-6(2)5-7-8(9(11)12)10(7,3)4/h5,7-8H,1-4H3,(H,11,12)/t7-,8+/m0/s1 Key: XLOPRKKSAJMMEW-JGVFFNPUSA-N
SMILES CC(=CC1C(C1(C)C)C(=O)O)C
Properties
Chemical formula	C10H16O2
Molar mass	168.236 g·mol−1
Melting point	17 °C (63 °F; 290 K) (1R,3R) or (+)-trans
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Biosynthesis

Chrysanthemic acid is derived from its pyrophosphate ester, which in turn is produced naturally from two molecules of dimethylallyl diphosphate.^[3]

Industrial synthesis

Chrysanthemic acid is produced industrially in a cyclopropanation reaction of a diene as a mixture of cis- and trans isomers, followed by hydrolysis of the ester:^[4]

Many pyrethroids are accessible by re-esterification of chrysanthemic acid ethyl ester - a perfume ingredient.