- Enantioselective Synthesis of the Sex Pheromone of Lichen Moth, Miltochrista calamine, and Its Diastereomer
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The synthesis of a Miltochrista calamine sex pheromone and its diastereomer has been developed. The key steps of the synthetic approach involved Evans' chiral auxiliaries and the addition of alkyne to aldehyde, which were firstly applied to prepare this sex pheromone and its diastereomer. The synthetic sex pheromone could be used to trap insects and study physiological and ecological questions of the lichen moth.
- Yuan, Gucheng,Liu, Jiawei,Yu, Shihang,Wang, Xueyang,Bian, Qinghua,Wang, Min,Zhong, Jiangchun
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- A New Asymmetric Synthesis of (S)-14-Methyloctadec-1-ene, the Sex Pheromone of the Peach Leafminer Moth
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Abstract: An asymmetric synthesis of 14-methyl-1-octadecene, the sex pheromone of thepeach leafminer moth has been achieved. Based on the asymmetric methylation ofchiral (S)-4-benzyloxazolidin-2-one, thecarbon chain of the target molecule was assembled through aC1+C10+C4+C3procedure. The γ-lactone was transformed into 4-(benzyloxy)butanoic acid andthen, with the induction of Evan’s template, a chiral methyl group wasintroduced to the position of the carboxylic group in 97percent de. After reduction and a couple of chemicaloperations, the designed key intermediate A1was obtained. The synthesis of another moiety was started from decane-1,10-diolwhich was selectively protected and oxidized. The long carbon chain wasinstalled according to a Wittig protocol. After deprotection, oxidization, andmethylenation, the target molecule was synthesized in 7 linear steps with anoverall yield of 30.3percent.
- Bai, Hongjin,Du, Zhen-Ting,He, Guo-Guo,Liu, Lu,Tang, Meng,Wei, Liang,Zhang, Tao
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p. 1089 - 1095
(2020/07/25)
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- Chemoselective Biohydrogenation of Alkenes in the Presence of Alkynes for the Homologation of 2-Alkynals/3-Alkyn-2-ones into 4-Alkynals/Alkynols
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The chemoselective hydrogenation of alkenes in the presence of alkynes is a very challenging transformation to achieve with traditional chemical methods. The development of an effective procedure to perform this transformation would enrich the tool-kit available to organic chemists for the development of useful synthetic routes, and the creation of novel structural motifs. The reduction of activated alkene bonds by ene-reductases (ERs) is completely chemoselective, because of the mechanism of the reaction. Thus, we investigated the use of ERs belonging to the Old Yellow Enzyme family for the reduction of α,β-unsaturated aldehydes with a conjugated C≡C triple bond at the γ position. This reaction was exploited as the key step for the development of an effective homologation route to convert aryl and alkyl substituted propynals and butynones into 4-alkynals and 4-alkynols, avoiding some troublesome or hazardous steps of known synthetic routes. (Figure presented.).
- Colombo, Danilo,Brenna, Elisabetta,Gatti, Francesco G.,Ghezzi, Maria Chiara,Monti, Daniela,Parmeggiani, Fabio,Tentori, Francesca
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p. 2638 - 2648
(2019/05/16)
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- Copper-Catalyzed Enantioselective Conjugate Addition to α,β-Unsaturated Aldehydes with Various Organometallic Reagents
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β-Substituted aldehydes constitute a very important class of compounds found in nature. Synthesis of this motif can be envisioned by C-C bond formation on enals. For this purpose, we report herein the development of enantioselective copper-catalyzed conjugate addition of various organometallic reagents to α,β-unsaturated aldehydes with (R)-H8BINAP, (R)-TolBINAP, and (R)-SEGPHOS as chiral ligands. Three sets of conditions were successfully developed and several enals were used. Reactivity and regio- and enantioselectivities were strongly dependent on reaction conditions and substrates. Good to excellent regio- and enantioselectivities were obtained with zinc reagents R2Zn and aluminum reagents R3Al. However, the asymmetric conjugate addition of Grignard reagents afforded only moderate to good regio- and enantioselectivities.
- Goncalves-Contal, Sylvie,Gremaud, Ludovic,Palais, La?titia,Babel, Lucille,Alexakis, Alexandre
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p. 3301 - 3308
(2016/09/12)
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- Cyclopropane intermediates in the synthesis of chiral alcohols with methyl-branched carbon skeleton. Application in the synthesis of insect pheromones
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Several chiral building blocks, (2R)-2-methylundec-10-en-1-ol, (3R)-3-methylheptan-1-ol, and (4R)-4-methyloctan-1-ol, have been synthesized using cyclopropane intermediate products. It has been shown that the obtained chiral alcohols can be used in the sy
- Kovalenko,Mineeva
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p. 934 - 942
(2014/10/15)
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- Copper-catalyzed asymmetric conjugate addition to challenging michael acceptors and synthesis of relevant target molecules
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We report herein the enantioselective Cu-catalyzed conjugate addition of organometallic reagents to sensitive Michael acceptors and their application to the synthesis of relevant target molecules. This is one of the most important methodologies to form a C-C bond in an enantioselective manner. A wide range of α,β-unsaturated aldehydes and β,γ-unsaturated-α- ketoesters has been successfully used. Reactivity, regioand enantioselectivities were strongly dependent on the reaction conditions, therefore moderate to very good results were obtained. Furthermore, γ-substituted-α-ketoesters were used as chiral building blocks for further derivatization with complete retention of the chiral information to obtain key compounds. Schweizerische Chemische Gesellschaft.
- Gremaud, Ludovic,Palais, Laetitia,Alexakis, Alexandre
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scheme or table
p. 196 - 200
(2012/07/28)
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- Catalytic enantioselective β-alkylation of α,β-unsaturated aldehydes by combination of transition-metal- and aminocatalysis: Total synthesis of bisabolane sesquiterpenes
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Branching out! The first co-catalytic enantioselective (up to 98:2 e.r.) β-alkylation of α,β-unsaturated aldehydes by combination of simple chiral amine and copper catalysts provides β-branched aldehydes in a one-pot protocol (see scheme). The methodology was applied to the short total syntheses of bisabolane sesquiterpenes (S)-(+)-curcumene, (E)-(S)-(+)-3- dehydrocurcumene and (S)-(+)-tumerone.
- Afewerki, Samson,Breistein, Palle,Pirttil?, Kristian,Deiana, Luca,Dziedzic, Pawel,Ibrahem, Ismail,C?rdova, Armando
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supporting information; experimental part
p. 8784 - 8788
(2011/09/15)
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- (5R,7R)-5-Methylheptadecan-7-ol: A novel sex pheromone component produced by a female lichen moth, Miltochrista calamina, in the family Arctiidae
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A methyl-branched heptadecanol was found in the pheromone gland extract of a female lichen moth, Miltochrista calamina (Arctiidae, Lithosiinae). GC-MS analyses of the alcohol and a hydrocarbon derived from it by subsequent treatments with methanesulfonyl chloride and LiAlD4 in microscale reactions indicated 5-methylheptadecan-7-ol (1) as one possible structure. The four stereoisomers of 1 in a ratio of 4:4:1:1 were prepared from (S)-b-citronellol with 60% ee, and were separated by a combination of achiral and chiral HPLC columns. The absolute configuration of each isomer was determined by the comparison with the chromatographic behaviors of other samples synthesized by a different scheme, which applied the Jacobsen hydrolytic kinetic resolution of racemic 1,2-epoxydodecane to fix the configuration of the 7-hydroxy group. Only the (5R,7R)-isomer attracted male moths; thus, we concluded that M. calamina females secrete (5R,7R)-1 as a sex pheromone, indicating a new chemical class of lepidopteran female sex pheromones.
- Yamakawa, Rei,Kiyota, Ryutaro,Taguri, Tomonori,Ando, Tetsu
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p. 5808 - 5811
(2011/12/14)
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- A general strategy for the introduction of stereogenic centers bearing a methyl group: Total synthesis of sex pheromones
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We're bringing sexy back: The highly efficient introduction of stereogenic centers bearing methyl group by conjugate addition of RMgBr to α,β-unsaturated esters has been employed in the total syntheses of two sex pheromones (see scheme). Binap=[1,1'-binaphthalene]-2,2'- diylbis(diphenylphosphane). Copyright
- Wang, Shun-Yi,Song, Ping,Chin, Yen-Jin,Loh, Teck-Peng
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supporting information; experimental part
p. 385 - 388
(2011/10/12)
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- Asymmetric conjugate silyl transfer in iterative catalytic sequences: Synthesis of the C7-C16 fragment of (+)-neopeltolide
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Matched or mismatched, that is not the question! The anti,anti configuration of the C7- C16 fragment of (+)-neopeltolide is stereoselectively installed in an iterative sequence of catalyst-controlled Si group and Me group transfers, even with mismatched selectivity in the former (Si=Me2PhSi, see scheme; TBS=tert-butyldimethylsilyl).
- Hartmann, Eduard,Oestreich, Martin
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supporting information; experimental part
p. 6195 - 6198
(2010/11/17)
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- Copper-catalyzed enantioselective 1,4-addition to α,β- unsaturated aldehydes
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Figure presented The first asymmetric Cu-catalyzed conjugate addition of dialkylzinc zinc reagents to a large scope of enals in presence of phosphoramidite, SimplePhos, or (R)-BINAP ligands with enantiomeric excesses up to 90% is reported. Moreover, ACA of Grignard reagents afforded moderate to good 1,4-regioselectivities with enantioselectivities up to 90%.
- Palais, Laetitia,Babel, Lucille,Quintard, Adrien,Belot, Sebastien,Alexakis, Alexandre
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supporting information; experimental part
p. 1988 - 1991
(2010/07/10)
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- An iterative catalytic route to enantiopure deoxypropionate subunits: Asymmetric conjugate addition of Grignard reagents to α,β-unsaturated thioesters
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A highly enantioselective (up to 96% ee) conjugate addition of Grignard reagents, in particular, MeMgBr, to α,β-unsaturated thioesters is provided as well as its application to a diastereo- and enantioselective iterative route to syn- and anti-1,3-dimethyl arrays and deoxypropionate subunits. The versatility of the method is illustrated in the synthesis of (-)-lardolure, a multimethyl-branched insect natural pheromone. Copyright
- Des Mazery, Renaud,Pullez, Maddalena,Lopez, Fernando,Harutyunyan, Syuzanna R.,Minnaard, Adriaan J.,Feringa, Ben L.
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p. 9966 - 9967
(2007/10/03)
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- Asymmetric conjugate addition of copper reagents to α,β- unsaturated tert-butanesulfinyl imines
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(Chemical Equation Presented) Addition of organocuprates to N-sulfinyl α,β-unsaturated imines proceeds in good yields and with good diastereoselectivities. α,β-Unsaturated sulfinyl ketimines and aldimines have both been shown to be suitable substrates for this reaction.
- McMahon, Jeffrey P.,Ellman, Jonathan A.
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p. 5393 - 5396
(2007/10/03)
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- The Remarkable Ability of Lithium Ion to Reverse the Stereoselectivity in the Conjugate Addition of Li[BuCuI] to a Chiral N-Crotonyl-2-oxazolidinone
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Equation presented. The influence of lithium ions on the conjugate addition of the monoorganocuprate reagent, Li[BuCuI], to a chiral crotonate has been investigated. The results show that iodotrimethylsilane (TMSI) is crucial for the asymmetric conjugate addition of the copper reagent, but only in THF or when 12-crown-4 is used. The reaction is thought not to involve any halosilane in any critical steps in the organocopper mechanisms conducted in Et 2O.
- Dambacher, Jesse,Bergdahl, Mikael
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p. 3539 - 3541
(2007/10/03)
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- Total synthesis of HUN-7293
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The first total synthesis of the cyclic heptadepsipeptide HUN-7293 (1), a potent inhibitor of cell adhesion molecule expression exhibiting anti-inflammatory properties, is detailed. The most effective approach relied on an unusually efficient macrocyclization with the formation of the MLEU3 - LEU4 secondary amide that potentially benefits from intramolecular H-bonding preorganization of the acyclic substrate. The requisite linear depsipeptide was convergently assembled with the late stage introduction of the linking ester enlisting a Mitsunobu esterification that occurs with inversion of the DGCN α-center permitting the utilization of a readily available L-amino acid precursor to the D α-hydroxy carboxylic acid residue. An alternative and similarly attractive approach of direct macrolactonization of a substrate necessarily incorporating a D-DGCN subunit proved viable albeit less effective. Biological evaluation in cellular assays for vascular adhesion molecule expression confirmed that synthetic HUN-7923 (1) is essentially indistinguishable from the naturally occurring cyclodepsipeptide.
- Boger, Dale L.,Keim, Holger,Oberhauser, Berndt,Schreiner, Erwin P.,Foster, Carolyn A.
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p. 6197 - 6205
(2007/10/03)
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- Asymmetric cleavage of chiral α,β-ethylenic acetals by organolithium reagents
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,β-Ethylenic chiral acetals react regio- and stereoselectively with organolithium reagents. The obtained enol ether may be hydrolyzed into a chiral β-disubstituted aldehyde.
- Alexakis, Alexandre,Mhamdi, Farida,Lagasse, Franz,Mangeney, Pierre
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p. 3343 - 3346
(2007/10/03)
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- Optical Isomers of 3,13-Dimethylheptadecane: Sex Pheromone Components of the Western False Hemlock Looper, Nepytia freemani (Lepidoptera: Geometridae)
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(3S,13R)-3,13-Dimethylheptadecane [(3S,13R)-3,13-dime-17Hy] is the major pheromone component of the western false hemlock looper (WFHL), Nepytia freemani. In comparative gas chromatographic-electroantennographic detection (GC-EAD) analyses of stereoselectively synthesized isomers, 1 pg of (3S,13R)-dime-17Hy elicited significantly stronger electrophysiological responses by male WFHL antennae than did 1 pg of separately injected (3R,13R)-, (3R,13S)- or (3S,13S)-3,13-dime-17Hy. In field experiments with individually tested stereoisomers, (3S,13R)-3,13-dime-17Hy was the only stereoisomer to attract males, but the four-stereoisomer blend was 3.6 times more attractive. Quaternary and all binary combinations of (3S,13R)-3,13-dime-17Hy with the other stereoisomers were equally attractive, suggesting that synergistic behavioral activity in WFHL resided with either one of (3R,13R)-, (3R,13S)-, or (3S,13S)-3,13-dime-17Hy. Because optical isomers of (di)methylhydrocarbons do not separate on currently available columns, it remains unknown whether female WFHL also produce a four-stereoisomer pheromone blend. Substitutionality of pheromone stereoisomers without loss of behavioural activity has not previously been reported, but favorably compares with the concept of pheromone redundancy that was first suggested for the multiple pheromone component blend of the cabbage looper moth, Trichoplusia ni.
- King, G. G. Skip,Gries, Regine,Gries, Gerhard,Slessor, K. N.
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p. 2027 - 2046
(2007/10/03)
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- ADDITION D'ORGANOCUPRATES AUX OXAZOLIDINES CHIRALES α-β ETHYLENIQUES : I - RESULTATS - EFFETS DE SEL ET DE SOLVANT
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Organocuprates add quantitatively to oxazolidines I.The steric course of the reaction can be reversed and the diastereoselectivity enhanced by salt effect and (or) by solvent effect.
- Berlan, J.,Besace, Y.,Pourcelot, G.,Cresson, P.
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p. 4757 - 4766
(2007/10/02)
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- HYDROFORMYLATION OF LESS REACTIVE OLEFINS WITH MODIFIED RHODIUM CATALYSTS
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The otherwise unreactive olefins (2-methyl-1-hexene, limonene, cyclohexene, methylene cyclohexane) are hydroformylated under mild conditions (90 deg C, 10 bar) in the presence of phosphite-modified rhodium catalysts.The high rates observed are attributed to the steric and electronic properties of these phosphite ligands and their ability to stabilize unsaturated rhodium species.Examples of these ligands are tris(o-t-butylphenyl) phosphite and tris(hexafluoroisopropyl) phosphite, which are, respectively, sterically demanding and strongly electron-withdrawing.
- Leeuwen, P. W. N. M. van,Roobeek, C. F.
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p. 343 - 350
(2007/10/02)
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