Chrysanthemate analogues

A new facile route to chrysanthemate analogues by 1,5-elimination from 6-bromo-alk-4-enoates and by 1,7-elimination from 8-bromoalka-4,6-dienoates has appeared. ... 

Cyclization of carbanions derived from bromo-esters of type (18) has been exploited by Kondo et al in a useful approach to chrysanthemic analogues (Scheme 9), and the related base-induced cyclizations of yS-unsaturated epoxides and of epoxysulphones o to appropriate cyclopropanes have also received attention. 

Phenothrin, (3-phenoxyphenyl)metliyl (+)-af,/ra chrysanthemate, a mixture of four isomers, has a rat oral LD5Q of >5000 mg/kg. Cyphenothrin is the a-CN-analogue of phenothrin (Table 3). It is a mixture of four isomers, and is soluble in water to 10 //g/L. The rat LD5Qs are 318 male, 419 female... 

The syntheses of phenothrin analogues of lower insecticidal activity and of other chrysanthemate esters have been reported. Further pyrethroid papers concern the relationship between insecticidal toxicity and cyclopropane substituents in pyret-hroids, the photochemistry of the most potent known pyrethroid,and the metabolism of permethrin in rats (c/. Vol. 6, p. 13). " ... 

The consistency of the high levels of enantiocontrol accessible in these diazoester cyclizations is underpinned by their growing applications in enantiose-lective synthesis of bioactive molecules containing cyclopropane units. Notable examples include the preparation of multifunctional cyclopropanes as peptide isosteres for renin inhibitors (Scheme 4) [42] presqualene alcohol from farnesyl diazoacetate (Scheme 5) [43] the GABA analogue 3-azabicyclo[3.1.0]hexan-2-one from N-allyldiazoacetamide, Eq. (26) [23] and precursors of lR,3S)-cis-chrysanthemic acid and the pheromone, E-(-)-dictyopterene C (Scheme 6) [44, 45],... 

Photochemical decomposition of pyrethrins and synthetic analogues can be slowed down by the simultaneous use of antioxidants and photoscreens. In the course of decomposition, chrysanthemic acid, phenylacetic acid, benzyl alcohol, benzaldehyde and benzoic acid are formed from resmethrin (32) as decomposition products and, at the same time, the furan ring undergoes an oxidative transformation (Ueda et al., 1974) ... 

Miscellaneous Reactions of Methylenephosphoranes.—The synthesis of three-membered rings by means of phosphorus ylides has been reviewed and there have been several new reports of this type of reaction. Optically active a,p-un-saturated esters have been converted into cyclopropanes highly stereoselectively by reaction with isopropylidenetriphenylphosphorane as the key step in syntheses of both (li ,3 )-chrysanthemic acid methyl ester (53) and the (IR) cis-gem dibromovinyl analogue (54). The addition of reactive phosphonium ylides to functionalized 1,3-butadienylphosphonates provides a new synthesis of 2-cyclopen ten-1 -ylphosphonates (5 5). ... 

A project directed towards the synthesis of chrysanthemic acid enantiomers illustrates some of our recent work on cyclopropano-pyranosides. The sequence (Scheme 40) that had worked so well (25) for the preparation of the simple cyclopropyl ketone (169) from the methanol adduct (168) was not adaptable for preparation of the gem-dimethyl analogue (171). The photoaddition of isopropanol to (83) gave an excellent yield of (170), but efforts to convert this into (171) were not encouraging. However, the Wittig cyclopropanation (24) of epoxide (51) gave the ester (172) whose stereochemistry was deduced by two pieces of nmr data (a) the value J12 < 1 Hz (76) (see Scheme 4), and (b) a ten percent Nuclear Overhauser Effect between H-1 and the methyl protons. 

Chrysanthemic acid [2,2-dimethyl-3-(2-methylpropenyl)-cyclopropane-carboxylic acid] and its halogen-substituted analogues Terguride-based CSP UV diode array and chiroptical detectors 26... 

Caron aldehyde ester was of great help particularly for the casual preparation of many chrysanthemic acid analogues for insecticidal research. Instead of triphenyl phosphine the trisdimethylamino phosphine may be apphed preferentially [247]. The production of caronaldehyde 755 by the route outUned above is still essential for the production of deltamethrin. Alternatively to the Wittig reaction, the dichlorome-thylene moiety may be introduced by reaction of carbenoids or carbanions from haloforms with the hemiketal 158 of free cis-caronaldehyde, (reaction scheme 100) [248, 249] and subsequently completed by dehalogenation processes. 

In the past carbohydrates have often proved useful as enantiomerically well defined starting materials. Now Fraser-Reid and Fitzsimmons have utilized (24) as starting material in a synthesis of both of the enantiomers of chrysanthemic acid in an optically pure state. ° The chrysanthemum dicarboxylic acid analogue (26)... 

In an extension of previous work, it has been found that Pd(0)-catalysed intramolecular cyclization of allylic acetates (21) can be used to prepare the chrysanthemic acid analogues (22). The potentially useful cw-cyclopropane (23) can be simply obtained by base-induced addition of cyanoacetate to ethyl 2-bromo-3,3-dimethylacrylate followed by decarboxylation oddly, a similar reaction using malonate fails to give a cyclopropane. Optically pure dichloro cw-chrysanthemic acid (26) has been obtained by a Favorskii rearrangement of the chiral cyclobutanone (25) prepared from the keten (24) by sequential [2 + 2]cycloaddition, cine-rearrangement, and resolution (Scheme 3). ... 

Several ingenious syntheses of the dichloro-analogue (15) of chrysanthemic acid, used in the formation of the new generation of insecticidal pyrethroids [e.g. cypermethrin (16)] have been published in the past few years. To add to this list are new methods based on the Favorski rearrangement and on an intramolecular carbene insertion reaction, and a further method based on the Wittig reaction. ... 

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