(+)-Trans-chrysanthemic acid from (+)-Δ3-carene

Pyrethroid insecticides Chapter IVa. Reactivity of chrysanthemic acid and its lower esters

“…42 It is usually achieved with 2N aqueous solution of sodium or potassium hydroxides in refluxing methanol for 1.5-4 h (See below, Scheme 62). [43][44][45][46][47] Saponification of ethyl chrysanthemate (trans/cis: 90/10) has been also performed using 5 equivalents of potassium hydroxide in aqueous ethanol (EtOH/H2O; 5/1) at 135°C for 3 h and delivers stereoselectively chrysanthemic acid (86%, trans/cis: 90/10). 11 Even under these drastic conditions, saponification is faster than epimerization that would have led to cis/trans epimerization.…”

“…Synthesis of vinylcyclopropane carboxylic acid chlorides using thionyl or oxalyl chlorides. The transformation of chrysanthemic acid (1aH) to chrysanthemoyl chloride (3aCl) has been routinely achieved with thionyl chloride due to its great availability and low cost (Scheme 27, entry a [43][44][45]57,[64][65][66][67]68 and more rarely using instead oxalyl chloride (Scheme 27, entry d). 40,69 In the former case, it has been suggested to use thionyl chloride purified using a well-established protocol.…”

“…Alkylation of chrysanthemic acid 31,51,72,[81][82][83] (Scheme 31) with diazomethane 84,85 is probably the most efficient synthetic method to produce their methyl esters especially for analytical purposes.…”

Chiral Cyclic Synthetic Intermediates from Readily Available Monoterpenoids

“…Ozonolysis of the trisubstituted double bond of (+)-car-3-ene 4 gives rise to the unsymmetrically substituted unit 8 in which the side arms can be differentiated as exemplified (Scheme 1) by the synthesis of (+)-trans-chrysanthemic acid 9. 6 The acetyl group was converted to an acetoxyl group by a Baeyer-Villiger reaction whilst the isopropyl group was created by a Grignard reaction of the ester with methylmagnesium iodide. The isomerisation of the substituents on the ring to afford the trans isomer was achieved by treatment with alkali.…”

A Facile and Efficient Synthesis of 3,3-Dimethyl Isopropylidene Proline From (+)-3-Carene

“…Alternatively, the hydroxy ester 7 could be readily cyclized to the corresponding lactone under refluxing conditions in the presence of catalytic amounts of DBU (Scheme ). Attempts to cyclize the acetate 6 or the corresponding hydrolyzed product 8 with p -TsOH led to the unexpected opening of the gem -substituted cyclopropane ring followed by rearrangement to lactone 9 (Scheme ).…”