- Decarboxylative alkenylation
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Olefin chemistry, through pericyclic reactions, polymerizations, oxidations, or reductions, has an essential role in the manipulation of organic matter. Despite its importance, olefin synthesis still relies largely on chemistry introduced more than three decades ago, with metathesis being the most recent addition. Here we describe a simple method of accessing olefins with any substitution pattern or geometry from one of the most ubiquitous and variegated building blocks of chemistry: alkyl carboxylic acids. The activating principles used in amide-bond synthesis can therefore be used, with nickel- or iron-based catalysis, to extract carbon dioxide from a carboxylic acid and economically replace it with an organozinc-derived olefin on a molar scale. We prepare more than 60 olefins across a range of substrate classes, and the ability to simplify retrosynthetic analysis is exemplified with the preparation of 16 different natural products across 10 different families.
- Edwards, Jacob T.,Merchant, Rohan R.,McClymont, Kyle S.,Knouse, Kyle W.,Qin, Tian,Malins, Lara R.,Vokits, Benjamin,Shaw, Scott A.,Bao, Deng-Hui,Wei, Fu-Liang,Zhou, Ting,Eastgate, Martin D.,Baran, Phil S.
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p. 213 - 218
(2017/05/19)
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- New catalytic system Cu(OAc)2-2,4-lutidine-ZnCl2 for olefin cyclopropanation with methyl diazoacetate
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A new efficient catalytic system consisting of Cu(OAc)2, 2,4-lutidine, and ZnCl2 was found for the cyclopropanation of unsaturated compounds with methyl diazoacetate. In the case of conjugated dienes, the process occurs regioselectively at the most alkylated C=C bond.
- Gareev,Sultanova,Biglova,Dokichev,Tomilov
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experimental part
p. 1784 - 1786
(2011/04/23)
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- Novel synthesis of (d,l) trans-chrysanthemic acid involving a β-diketone fragmentation
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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.
- Krief, Alain,Jeanmart, Stephane
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p. 6167 - 6168
(2007/10/03)
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- An expeditious enantioselective synthesis of methyl trans-chrysanthemate
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Methyl trans-chrysanthemate has been prepared in few steps from isopropylidenediphenylsulfurane and methyl (E)-3-(3,3-dimethyloxiran-2-yl)prop-2-enoate. The latter was obtained from methyl 4-oxobutenoate or 3-methylbut-2-en-1-ol. The Sharpless catalytic epoxidation reaction allows an asymmetric version of this transformation.
- Krief, Alain,Dumont, Willy,Baillieul, Diane
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p. 2019 - 2022
(2007/10/03)
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- Stereoselective synthesis of methyl trans-chrysanthemate and related derivatives
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γ-hydroxyalkenylstannanes, readily available from α,β- unsaturated esters, α,β-unsaturated aldehydes and tri(n- butyl)stannyllithium, react with boron trifluoride etherate to produce vinyl cyclopropane carboxylic esters. An original highly convergent synthesis of chrysanthemic acid is reported.
- Krief, Alain,Provins, Laurent
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p. 2017 - 2020
(2007/10/03)
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- Enantioselectivity and cis/trans-Selectivity in Dirhodium(II)-Catalyzed Addition of Diazoacetates to Olefins
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The RhII-catalyzed carbenoid addition of diazoacetates to olefins was investigated with 4> (1; phox = tetrakis), 4> (2; mepy = tetrakismethyl (2S)-tetrahydro-5-oxopyrrole-2-ca
- Mueller, Paul,Baud, Corine,Ene, Doina,Motallebi, Sharokh,Doyle, Michael P.,et al.
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p. 459 - 470
(2007/10/02)
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- Stereospecific reaction of an α-sulfonyl carbanion through chelation
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Intramolecular chelation as presented in formula 6 is proposed to explain asymmetric induction of reactions of the carbanion derived from sulfone 10.The designed molecule 10 was obtained from reaction of camphor lithium enolate derived from (+)-camphor (1R,4R bornan-2-one) with sulfur dioxide followed by 3-methyl-2-butenyl bromide to give the keto sulfone 9 which was reduced by LAH to the hydroxysulfone 10.The dianion prepared by action of n-butyllithium gave, with methyl iodide, the mono-methylated product 14 with a diastereomeric excess better than 96percent.The structure of the methylated product was determined by X-ray diffraction.The R configuration at the new asymmetric carbon corresponds to an inversion in the methylation reaction if the species has a chelated structure like 6.With excess of methyl iodide, the C- and O-methylated product 15 was obtained.In the presence of HMPA, the stereoselectivity was lower.The reaction of the carbanion derived from sulfone 10, with methyl 3-methylbut-2-enoate requires the presence of HMPA and leads to chrysanthemic ester 17 with 25percent e.e.
- Singh, N. P.,Metz, B.,Biellmann, J. F.
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- 2-Metallo-2-nitropropanes as Isopropylidene Transfer Reagents for the Cyclopropanation of Electrophilic Alkenes. Application to the Synthesis of trans-Chrysanthemic Acid
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2-Metallo-2-nitropropanes have been successfully used for the cyclopropanation of electrophilic alkenes and act as isopropylidene transfer reagents.
- Krief, A.,Hevesi, L.,Chaboteaux, G.,Mathy, P.,Sevrin, M.,Vos, M. J. De
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p. 1693 - 1695
(2007/10/02)
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- Cycloaddition 1,3-dipolaire du dimethyldiazomethane sur des esters et nitriles polyeniques. Acces aux esters cis et trans chrysanthemiques a partir des esters δ-methylsorbiques Z et E
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The dipolar cycloaddition reaction of 2-diazopropane with several dienic and trienic dipolarophiles is described.Methyl sorbate and methyl δ-bromomethylsorbates lead solely to Δ2-pyrazolines which result from a direct "Michael" addition.Methyl δ-methylsorbates and the corresponding nitriles on the contrary give unexpectedly also Δ1-pyrazolines, via an inverse cycloaddition.These are conveniently transformed by thermolysis or photolysis into chrysanthemic esters or nitrile.In the case of the trienic ester 15, the cycloaddition permits the characterisation of two regioisomeric Δ1-pyrazolines, the direct adduct being however poorly stable.This allows nevertheless the study of their respective thermolysis.While the inverse adduct leads solely to a dienic chrysanthemic analog, the thermal fragmentation of the other one gives mainly, via di ?-methane rearrangement, an acyclic 1,4,6 triene ester.
- Franck-Neumann, Michel,Miesch, Michel
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p. 362 - 370
(2007/10/02)
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- Mechanistic Study of the Thermal Acid-catalysed Rearrangement of trans-methyl Chrysanthemate to Lavandulyl Derivatives
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trans-Methyl chrysanthemate (17) under acid conditions at room temperature rearranged to the lavandulyl esters: methyl trans-5-methyl-2-propen-2-ylhex-3-enoate (18) and methyl trans-5-methyl-2-(2-hydroxypropan-2-yl)hex-3-enoate (19) which was formed by cyclopropylcarbinylhomoallyl rearrangement.Both (18) and (19) further isomerise and dehydrate to the stable methyl trans-5-methyl-2-propan-2-ylidenehex-3-enoate (20).Under similar acidic conditions, (18) and (19) each gave a mixture of lavandulyl esters and (17); minor amounts of side products, methyl trans-5-methylhex-3-enoate (21), methyl trans-5-methyl-2-(2-methoxypropan-2-yl)hex-3-enoate (22), methyl cis-5-methyl-2-propen-2-ylhex-2-enoate (23) were detected after some time.Acid methanolysis of (17) gave a substantial amount of (22) and its isomer, methyl 2,2-dimethyl-3-(2-methoxypropan-2-yl)cyclopropanecarboxylate (26).There was also found in low concentration, methyl trans-5-methyl-2-propan-2-ylhex-3-enoate (24) and methyl 5-methyl-2-propan-2-ylidenehexanoate (25) possibly the result of a hydride transfer from the solvent.Deuterium exchange was observed in the isobutenyl side-chain of (17) and the isobutenyl moiety of (18) and (19).At 130 deg C under similar acidic conditions a mixture of unsaturated γ- and δ-lactones was obtained from (17).The principal lactone was dihydro-5-propan-2-yl-3-propan-2-ylidenefuran-2(3H)-one (29).Mechanisms for the formation of these products are discussed.The fact that lavandulyl derivatives were obtained may shed new light on the biogenesis of chrysanthemic acid in plants.
- Goldschmidt, Zeev,Crammer, Bernard,Ikan, Raphael
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p. 2697 - 2705
(2007/10/02)
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- TRANSITION-METAL-CATALYSED REACTIONS OF DIAZOESTERS : SYNTHESIS OF CHRYSANTHEMIC AND PERMETHRIC ACID ESTERS BY CYCLOPROPANATION OF CONJUGATED DIENES
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Pyrethroid precursors (permethric and chrysanthemic acid esters) are efficiently synthesized by rhodium(II)-catalysed cyclopropanation of the properly substituted conjugated diene.Reaction selectivities depend on both the catalyst counter-ion and the diazoester alkoxy-group (carbene precursor) and are attributed to non-bonded interactions.
- Demonceau, A.,Noels, A. F.,Anciaux, A. J.,Hubert, A. J.,Teyssie, P.
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p. 949 - 952
(2007/10/02)
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- STEREOSPECIFIC CYCLOPROPENIC SYNTHESIS OF CIS-CHRYSANTHEMIC METHYL ESTER. 2. THE BY-PASSING DIAZOALKANE WAY (1).
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A stereospecific synthesis of cis-chrysanthemate by catalytic hydrogenation of a cyclopropene is described.The required precursor, a 3H-pyrazole, is obtained here via a novel dianion reaction and MnO2 dehydrogenation of a Δ2-pyrazoline, instead of the more cumbersome diazoaddition method.
- Franck-Neumann, M.,Miesch, M.
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p. 1409 - 1412
(2007/10/02)
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