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Alain Krief - One of the best experts on this subject based on the ideXlab platform.
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syntheses of racemic and scalemic cis Chrysanthemic Acid from β γ unsaturated cyclohexanol
Helvetica Chimica Acta, 2012Co-Authors: Alain Krief, Stephane Jeanmart, Humaira Yasmeen Gondal, Adrian KremerAbstract:2,2,5,5-Tetramethylcyclohexane-1,3-dione is a valuable starting-material precursor of cis-Chrysanthemic Acid. The (1S)-stereoisomer is a precursor of pyrethrin I, the most active natural insecticide from Chrysanthemum cinerariifolium, whereas the (1R)-stereoisomer is efficiently transformed to deltamethrin, the most active commercially available pyrethroid insecticide. Several intermediates have been identified and used with variable success for that purpose.
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novel synthesis of d l cis Chrysanthemic Acid involving α α dibromination of 2 2 5 5 tetramethylcyclohexane 1 3 dione application to the enantioselective synthesis of 1r cis Chrysanthemic Acid
Tetrahedron Letters, 2009Co-Authors: Alain Krief, Willy Dumont, Adrian KremerAbstract:Abstract cis-Chrysanthemic Acid has been prepared in a few steps from dimethyldimedone via dibromination at alpha positions of each carbonyl carbons. The trans-dibromide which is almost exclusively formed has been isomerized to its cis-stereoisomer by highly chemoselective tandem H/K–K/H exchanges involving potassium bases at low temperature (
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selected regiocontrolled transformations applied to the synthesis of 1s cis Chrysanthemic Acid from 1s 3 4 epoxy 2 2 5 5 tetramethylcyclohexanol
ChemInform, 2009Co-Authors: Alain Krief, Humaira Yasmeen Gondal, Adrian KremerAbstract:(1S)-cis-Chrysanthemic Acid has been prepared in a few steps with complete control of the relative and absolute stereochemistry using regiocontrolled epoxide ring opening, diol mono-oxidation and cyclopropanation.
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diastereoselective epoxidation of compound bearing a cyclohex 3 enol moiety application to the enantioselective synthesis of 1r trans Chrysanthemic Acid and 1r cis deltametrinic Acid
Heterocycles, 2008Co-Authors: Alain Krief, Stephane Jeanmart, Adrian KremerAbstract:We disclose the synthesis of enantiomeric (1S)-cis- and (lR)-cis-Chrysanthemic Acids precursors of S-bioallethrin and deltamethrin the most active indoor and outdoor insecticides respectively. It involves an original strategy which takes advantage of the complete stereocontrolled epoxidation of an homoallylalcohol and the synthesis in the same pot of precursors of each of the two enantiomers of cis-Chrysanthemic Acid, bearing functional groups possessing similar reactivity but having different structural behavior which allow their easy separation.
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fragmentation of 4 sulfonylbicyclo 3 1 0 hexan 2 ones as the key step in the enantioselective synthesis of 1r cis Chrysanthemic Acid involving desymmetrization of 3 3 6 6 tetramethylbicyclo 3 1 0 hexane 2 4 dione
Synlett, 2007Co-Authors: Alain Krief, Adrian KremerAbstract:t-BUOK-H 2 O (7.6:2.3) in THF or DMSO allows the efficient Grob-type fragmentation of4-sulfonyl-bicyclo[3.1.0]hexan-2-ones which cannot be achieved by potassium hydroxide in DMSO as we originally described.
Adrian Kremer - One of the best experts on this subject based on the ideXlab platform.
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syntheses of racemic and scalemic cis Chrysanthemic Acid from β γ unsaturated cyclohexanol
Helvetica Chimica Acta, 2012Co-Authors: Alain Krief, Stephane Jeanmart, Humaira Yasmeen Gondal, Adrian KremerAbstract:2,2,5,5-Tetramethylcyclohexane-1,3-dione is a valuable starting-material precursor of cis-Chrysanthemic Acid. The (1S)-stereoisomer is a precursor of pyrethrin I, the most active natural insecticide from Chrysanthemum cinerariifolium, whereas the (1R)-stereoisomer is efficiently transformed to deltamethrin, the most active commercially available pyrethroid insecticide. Several intermediates have been identified and used with variable success for that purpose.
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novel synthesis of d l cis Chrysanthemic Acid involving α α dibromination of 2 2 5 5 tetramethylcyclohexane 1 3 dione application to the enantioselective synthesis of 1r cis Chrysanthemic Acid
Tetrahedron Letters, 2009Co-Authors: Alain Krief, Willy Dumont, Adrian KremerAbstract:Abstract cis-Chrysanthemic Acid has been prepared in a few steps from dimethyldimedone via dibromination at alpha positions of each carbonyl carbons. The trans-dibromide which is almost exclusively formed has been isomerized to its cis-stereoisomer by highly chemoselective tandem H/K–K/H exchanges involving potassium bases at low temperature (
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selected regiocontrolled transformations applied to the synthesis of 1s cis Chrysanthemic Acid from 1s 3 4 epoxy 2 2 5 5 tetramethylcyclohexanol
ChemInform, 2009Co-Authors: Alain Krief, Humaira Yasmeen Gondal, Adrian KremerAbstract:(1S)-cis-Chrysanthemic Acid has been prepared in a few steps with complete control of the relative and absolute stereochemistry using regiocontrolled epoxide ring opening, diol mono-oxidation and cyclopropanation.
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diastereoselective epoxidation of compound bearing a cyclohex 3 enol moiety application to the enantioselective synthesis of 1r trans Chrysanthemic Acid and 1r cis deltametrinic Acid
Heterocycles, 2008Co-Authors: Alain Krief, Stephane Jeanmart, Adrian KremerAbstract:We disclose the synthesis of enantiomeric (1S)-cis- and (lR)-cis-Chrysanthemic Acids precursors of S-bioallethrin and deltamethrin the most active indoor and outdoor insecticides respectively. It involves an original strategy which takes advantage of the complete stereocontrolled epoxidation of an homoallylalcohol and the synthesis in the same pot of precursors of each of the two enantiomers of cis-Chrysanthemic Acid, bearing functional groups possessing similar reactivity but having different structural behavior which allow their easy separation.
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fragmentation of 4 sulfonylbicyclo 3 1 0 hexan 2 ones as the key step in the enantioselective synthesis of 1r cis Chrysanthemic Acid involving desymmetrization of 3 3 6 6 tetramethylbicyclo 3 1 0 hexane 2 4 dione
Synlett, 2007Co-Authors: Alain Krief, Adrian KremerAbstract:t-BUOK-H 2 O (7.6:2.3) in THF or DMSO allows the efficient Grob-type fragmentation of4-sulfonyl-bicyclo[3.1.0]hexan-2-ones which cannot be achieved by potassium hydroxide in DMSO as we originally described.
Stephane Jeanmart - One of the best experts on this subject based on the ideXlab platform.
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syntheses of racemic and scalemic cis Chrysanthemic Acid from β γ unsaturated cyclohexanol
Helvetica Chimica Acta, 2012Co-Authors: Alain Krief, Stephane Jeanmart, Humaira Yasmeen Gondal, Adrian KremerAbstract:2,2,5,5-Tetramethylcyclohexane-1,3-dione is a valuable starting-material precursor of cis-Chrysanthemic Acid. The (1S)-stereoisomer is a precursor of pyrethrin I, the most active natural insecticide from Chrysanthemum cinerariifolium, whereas the (1R)-stereoisomer is efficiently transformed to deltamethrin, the most active commercially available pyrethroid insecticide. Several intermediates have been identified and used with variable success for that purpose.
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diastereoselective epoxidation of compound bearing a cyclohex 3 enol moiety application to the enantioselective synthesis of 1r trans Chrysanthemic Acid and 1r cis deltametrinic Acid
Heterocycles, 2008Co-Authors: Alain Krief, Stephane Jeanmart, Adrian KremerAbstract:We disclose the synthesis of enantiomeric (1S)-cis- and (lR)-cis-Chrysanthemic Acids precursors of S-bioallethrin and deltamethrin the most active indoor and outdoor insecticides respectively. It involves an original strategy which takes advantage of the complete stereocontrolled epoxidation of an homoallylalcohol and the synthesis in the same pot of precursors of each of the two enantiomers of cis-Chrysanthemic Acid, bearing functional groups possessing similar reactivity but having different structural behavior which allow their easy separation.
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Trends in Chrysanthemic Acid Chemistry: A Survey of Recent Pyrethrum Syntheses
Australian Journal of Chemistry, 2003Co-Authors: Stephane JeanmartAbstract:Nearly 80 years have passed since Staudinger and Ruzicka elucidated the structure of the active constituents of the insecticidal powder obtained from pyrethrum flowers (Tactenum cinerariaefolium, formerly Chrysanthemum cinerariaefolium, Figure 1).[1–4] As soon as the structures and absolute configurations of the six insecticidal esters (1a)– (1f) (Scheme 1, Table 1) naturally present in the extract had been fully confirmed,[5–8] synthetic analogues were investigated in attempts to elucidate the principles governing their activity and to discover more potent insecticides.[9] Developments in this field have led to a new generation of pyrethroids, such as (S)-bioallethrin (2), permethrin (3), and deltamethrin (4)[10] (Scheme 2), with greater insecticidal activity or a faster knockdown effect than the natural esters, as well as enhanced photostability.[10,11] Synthetic pyrethroids have therefore emerged to replace DDT (5) in crop protection; to their advantage they combine both low mammalian toxicity[12]∗ and biodegradability with high activity against a large number of insect types.
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novel synthesis of d l trans Chrysanthemic Acid involving a β diketone fragmentation
Tetrahedron Letters, 2002Co-Authors: Alain Krief, Stephane JeanmartAbstract:Methyl (d,l) trans-chrysanthemate as well as its cis-diastereoisomer have been prepared from dimethyl dimedone, one of their isomers, in a few steps and with complete control of the relative stereochemistry.
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Isomerisation of 2,2-dimethyl dimedone to (d,l) cis-Chrysanthemic Acid†
Tetrahedron Letters, 2000Co-Authors: Alain Krief, Guillaume Lorvelec, Stephane JeanmartAbstract:Abstract ( d , l ) cis -Chrysanthemic Acid has been obtained in four steps from 2,2-dimethyl dimedone which involves Bamford–Stevens olefination and tandem cyclization–Grob fragmentation reactions.
Eran Pichersky - One of the best experts on this subject based on the ideXlab platform.
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pyrethric Acid of natural pyrethrin insecticide complete pathway elucidation and reconstitution in nicotiana benthamiana
New Phytologist, 2019Co-Authors: Anthony L Schilmiller, Maarten A Jongsma, Henriette D L M Van Eekelen, Ric C H De Vos, Eran PicherskyAbstract:In the natural pesticides known as pyrethrins, which are esters produced in flowers of Tanacetum cinerariifolium (Asteraceae), the monoterpenoid acyl moiety is pyrethric Acid or Chrysanthemic Acid. We show here that pyrethric Acid is produced from chrysanthemol in six steps catalyzed by four enzymes, the first five steps occurring in the trichomes covering the ovaries and the last one occurring inside the ovary tissues. Three steps involve the successive oxidation of carbon 10 (C10) to a carboxylic group by TcCHH, a cytochrome P450 oxidoreductase. Two other steps involve the successive oxidation of the hydroxylated carbon 1 to give a carboxylic group by TcADH2 and TcALDH1, the same enzymes that catalyze these reactions in the formation of Chrysanthemic Acid. The ultimate result of the actions of these three enzymes is the formation of 10‐carboxyChrysanthemic Acid in the trichomes. Finally, the carboxyl group at C10 is methylated by TcCCMT, a member of the SABATH methyltransferase family, to give pyrethric Acid. This reaction occurs mostly in the ovaries. Expression in N. benthamiana plants of all four genes encoding aforementioned enzymes, together with TcCDS, a gene that encodes an enzyme that catalyzes the formation of chrysanthemol, led to the production of pyrethric Acid.
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production of trans Chrysanthemic Acid the monoterpene Acid moiety of natural pyrethrin insecticides in tomato fruit
Metabolic Engineering, 2018Co-Authors: Daniel B Lybrand, Stefan Bennewitz, Alain Tissier, Eran PicherskyAbstract:The pyrethrum plant, Tanacetum cinerariifolium (Asteraceae) synthesizes a class of compounds called pyrethrins that have strong insecticidal properties but are safe to humans. Class I pyrethrins are esters of the monoterpenoid trans-Chrysanthemic Acid with one of three jasmonic-Acid derived alcohols. We reconstructed the trans-Chrysanthemic Acid biosynthetic pathway in tomato fruits, which naturally produce high levels of the tetraterpene pigment lycopene, an isoprenoid which shares a common precursor, dimethylallyl diphosphate (DMAPP), with trans-Chrysanthemic Acid. trans-Chrysanthemic Acid biosynthesis in tomato fruit was achieved by expressing the chrysanthemyl diphosphate synthase gene from T. cinerariifolium, encoding the enzyme that uses DMAPP to make trans-chrysanthemol, under the control of the fruit specific promoter PG, as well as an alcohol dehydrogenease (ADH) gene and aldehyde dehydrogenase (ALDH) gene from a wild tomato species, also under the control of the PG promoter. Tomato fruits expressing all three genes had a concentration of trans-Chrysanthemic Acid that was about 1.7-fold higher (by weight) than the levels of lycopene present in non-transgenic fruit, while the level of lycopene in the transgenic plants was reduced by 68%. Ninety seven percent of the diverted DMAPP was converted to trans-Chrysanthemic Acid, but 62% of this Acid was further glycosylated. We conclude that the tomato fruit is an alternative platform for the biosynthesis of trans-Chrysanthemic Acid by metabolic engineering.
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coexpression analysis identifies two oxidoreductases involved in the biosynthesis of the monoterpene Acid moiety of natural pyrethrin insecticides in tanacetum cinerariifolium
Plant Physiology, 2018Co-Authors: Gaurav D Moghe, Krystle Wiegertrininger, Anthony L Schilmiller, Cornelius S Barry, Eran PicherskyAbstract:Flowers of Tanacetum cinerariifolium produce a set of compounds known collectively as pyrethrins, which are commercially important pesticides that are strongly toxic to flying insects but not to most vertebrates. A pyrethrin molecule is an ester consisting of either trans-Chrysanthemic Acid or its modified form, pyrethric Acid, and one of three alcohols, jasmolone, pyrethrolone, and cinerolone, that appear to be derived from jasmonic Acid. Chrysanthemyl diphosphate synthase (CDS), the first enzyme involved in the synthesis of trans-Chrysanthemic Acid, was characterized previously and its gene isolated. TcCDS produces free trans-chrysanthemol in addition to trans-chrysanthemyl diphosphate, but the enzymes responsible for the conversion of trans-chrysanthemol to the corresponding aldehyde and then to the Acid have not been reported. We used an RNA sequencing-based approach and coexpression correlation analysis to identify several candidate genes encoding putative trans-chrysanthemol and trans-chrysanthemal dehydrogenases. We functionally characterized the proteins encoded by these genes using a combination of in vitro biochemical assays and heterologous expression in planta to demonstrate that TcADH2 encodes an enzyme that oxidizes trans-chrysanthemol to trans-chrysanthemal, while TcALDH1 encodes an enzyme that oxidizes trans-chrysanthemal into trans-Chrysanthemic Acid. Transient coexpression of TcADH2 and TcALDH1 together with TcCDS in Nicotiana benthamiana leaves results in the production of trans-Chrysanthemic Acid as well as several other side products. The majority (58%) of trans-Chrysanthemic Acid was glycosylated or otherwise modified. Overall, these data identify key steps in the biosynthesis of pyrethrins and demonstrate the feasibility of metabolic engineering to produce components of these defense compounds in a heterologous host.
Paolo Righi - One of the best experts on this subject based on the ideXlab platform.
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the racemate cage influence of p 1 n 1 salt occurrence on enantiomer separation processes the case of trans Chrysanthemic Acid
Chemical Communications, 2007Co-Authors: Goffredo Rosini, Valerio Borzatta, Emanuela Marotta, Francesca Boschi, Gabriele Candido, Paolo RighiAbstract:The occurrence of p1,n1salt when accompanied by substrate self-association can have profound effects on enantiomer separation processes of non-racemic mixtures, impeding the complete recovery of the major enantiomer through formation of an inescapable racemate cage.
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the same and not the same similarities and differences in the resolution of trans Chrysanthemic Acid of industrial origin by the enantiomers of some threo 1 aryl 2 dimethylamino 1 3 propanediols
Green Chemistry, 2007Co-Authors: Goffredo Rosini, Valerio Borzatta, Claudia Ayoub, Emanuela Marotta, Andrea Mazzanti, Paolo RighiAbstract:The enantiomers of threo-dimethylamino-1-[4-(methylthio)phenyl]propane-1,3-diol (MTDP) were found to be effective resolving agents for trans-Chrysanthemic Acid (trans-ChA) on an industrial scale. (1S,2S)-(+)-MTDP and (1R,2R)-(−)-MTDP were revealed to be “blind” towards the enantiomers of cis-ChA. They work well on racemic and/or scalemic trans/cis mixtures of industrial production and are used in a stoichiometric amount with respect to the enantiomer of trans-ChA to be collected. Isopropyl ether is the solvent of choice, and it does not need the presence of co-solvents such as methanol to promote nucleation and crystal growth of the n salts as previously reported for threo-dimethylamino-1-[4-(nitro)phenyl]propane-1,3-diol (DMAD) enantiomers. X-ray crystal structures of the n salts of trans-ChA and MTDP revealed the peculiar features of two pseudopolymorphs. MTDP enantiomers are low cost, non-toxic, safe, and easily available from important precursors of thiamphenicol through a single straightforward reaction. After the resolution, they can be recovered almost quantitatively and reused without any loss of their chiral integrity. Similarities and differences of these resolving agents for trans-ChA with respect the behaviour of the enantiomers of DMAD and of the enantiomers of the parent compound, 1-phenyl-2-dimethylamino-1,3-propane-diol (DMPP), are shown in a comparative analysis of their performances.
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p1 n1 salts self assembled supramolecular structures sequestering racemates diastereomeric separation and enantiomeric enrichment of trans Chrysanthemic Acid
Chemical Communications, 2006Co-Authors: Goffredo Rosini, Valerio Borzatta, Claudia Ayoub, Emanuela Marotta, Andrea Mazzanti, Paolo RighiAbstract:The occurrence of p1,n1 salts can be exploited to sequester racemates; an application to technical mixtures of Chrysanthemic Acids (ChA) allowed the separation of trans- and cis-ChA and the recovery of the excess enantiomer of trans-ChA.