Conjugate Addition Of Organocuprates Research Articles

Aggregation pheromone of coconut rhinoceros beetle,Oryctes rhinoceros (L.) (coleoptera: Scarabaeidae)

Male coconut rhinoceros beetles,Oryctes rhinoceros (L.), produce three sex-specific compounds, ethyl 4-methyloctanoate, ethyl 4-methylheptanoate, and 4-methyloctanoic acid, the first of which is an aggregation pheromone. Synthesis of these compounds involving conjugate addition of organocuprates to ethyl acrylate is reported. In field trapping experiments, (4S)-ethyl 4-methyloctanoate and the racemic mixture were equally attractive and 10 times more effective in attracting beetles than ethyl chrysanthemumate, a previously recommended attractant. Ethyl 4-methylheptanoate was as attractive as ethyl chrysanthemumate and more attractive than 4-methyloctanoic acid, but further studies are required before it can be classed as an aggregation pheromone. Compared to ethyl 4-methyloctanoate alone, combinations of the three male-produced compounds did not increase attraction, whereas addition of freshly rotting oil palm fruit bunches to pheromone-baited traps significantly enhanced attraction. With increasing dose, captures ofO. rhinoceros increased, but doses of 6, 9, and 18 mg/day were competitive with 30 mg/day lures. Newly designed vane traps were more effective in capturing beetles than were barrier or pitfall traps. Results of this study indicate that there is potential for using ethyl 4-methyloctanoate in operational programs to controlO. rhinoceros in oil palm plantations.

ChemInform Abstract: Effective Enantiocontrol in Conjugate Additions of Organocuprates. Highly Selective 1,5‐Chiral Induction in the Conjugate Additions of Cuprates to α,β‐Unsaturated Amide Derivatives of 2,2‐ Dimethyloxazolidine Chiral Auxiliaries.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Effective Enantiocontrol in Conjugate Additions of Organocuprates. Highly Selective 1,5-Chiral Induction in the Conjugate Additions of Cuprates to .alpha.,.beta.-Unsaturated Amide Derivatives of 2,2-Dimethyloxazolidine Chiral Auxiliaries

Effective Enantiocontrol in Conjugate Additions of Organocuprates. Highly Selective 1,5-Chiral Induction in the Conjugate Additions of Cuprates to .alpha.,.beta.-Unsaturated Amide Derivatives of 2,2-Dimethyloxazolidine Chiral Auxiliaries

ChemInform Abstract: Conjugate Addition of Organocuprates to Methyl Crotonate Linked to Chiral Oxazolidones.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Highly Diastereoselective Conjugate Addition of Organocuprate to Acyclic E‐ and Z‐Enones: Reversal Stereoselectivity Under Kinetic and Thermodynamic Conditions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Conjugate Addition of Organocuprates to Methyl Crotonate Linked to Chiral Oxazolidones

Abstract Conjugate addition of various sp3 dialkylcuprates were performed on enoates 4a-b, γ-aminocrotonate equivalents embodied in chiral oxazolidones. The diastereoselectivity is good to moderate and allows the access to homochiral β-substituted GABA analogues.

Synthesis of (-)-Heliotridane and (-)-Isoretronecanol via Diastereoselective Conjugate Addition of Organocuprates to an Enoate Deriving from Proline

A synthesis of the pyrrolizidine alkaloids (-)-heliotridane and (-)-isoretronecanol and their epimers is described. The key step involves a diastereoselective conjugate addition of organocuprates to (2S)-N-(tertbutoxycarbonyl)-2-[(E)-3'-methoxy-3'-oxo-1'-propenyl]pyrrolidine (2) deriving from (S)-proline

Enantioselective conjugate addition of organocuprate using a chiral amidophosphine ligand

Based on the concept of a metal differentiating coordination, a new chiral amidophosphine ligand 2 was designed, synthesized, and applied in an enantioselective conjugate addition of lithium dimethylcuprate to chalcone providing the corresponding adduct in 84% ee.

Homochiral α,β-unsaturated γ-lactams: Versatile templates

The enantiomerically pure crystalline α,β-unsaturated γ-lactams 4 and 5 have been synthesized by utilizing 2,3-O-isopropylidene- D-glyceraldehyde ( 3) as chiral source and novel N-tert-butoxycarbonyl-2-(tert-butyldimethylsiloxy)pyrrole (TBSOP) as four carbon homologative reagent. Unsaturated lactam 4 has been selectively elaborated into hydroxylated pyrrolidinones 7, 8, and 11 by stereocontrolled procedures involving conjugate addition of organocuprates, cis-dihydroxylation, and α-alkylation via hydrogenation and enulate formation. The absolute stereochemistries of 4 and 5 have been secured by single crystal X-ray analyses.

Enantioselective Conjugate Addition Greatly Improves the Synthesis of (+)-Confertin

Enantioselective realization of the chirogenic isopropenylation of 1 (chem.yield:88%), mediated by a ligand-modified organocuprate: The five-membered ring building blocks 2+3 are enantioselectively produced by conjugate addition of a chiral ligand-modified organocuprate to 2-methylcyclopent-2-enone ( 1) (chemical yield: 88%; e.e.: 88%) and successfully converted in a multi-step sequence, after final enantioselection by recrystallization of an appropriate intermediate, into the pseudoguaianolide (+)-confertin ( 5).

Synthesis of inhibitors of 2,3-oxidosqualene-lanosterol cyclase: conjugate addition of organocuprates to N-(carbobenzyloxy)-3-carbomethoxy-5,6-dihydro-4-pyridone.

Synthesis of ammonium ion analogues of the first cationic intermediate, 5, presumed to be formed during the cyclization of 2,3-oxidosqualene by 2,3-oxidosqualene-lanosterol cyclase are reported. The required 2,3-substituted-4-piperidinols are prepared by conjugate addition of higher order alkyl (2-thienyl)(cyano)cuprates to 1-(carbobenzyloxy)-3-carbomethoxy-5,6-dihydro-4-pyridone. The nitrogen protecting group (carbobenzyloxy) is key to the synthesis in that it allows the conjugate addition to proceed in high yield and is easily converted to the required N-methyl group in the final products

4'-modified analogues of aristeromycin and neplanocin A: synthesis and inhibitory activity toward S-adenosyl-L-homocysteine hydrolase.

The carbocyclic adenosine analogues aristeromycin and neplanocin A both display significant S-adenosyl-L-homocysteine (AdoHcy) hydrolase inhibitory activity and broad-spectrum antiviral effects. Since phosphorylation of the 4'-hydroxymethyl substituent has been implicated with the cytotoxicity of these compounds, various analogues modified at this position were synthesized utilizing a key cyclopentenone intermediate 3 which can be derived from several members of the natural chiral pool. Cyclopentenone 3 underwent a highly stereoselective conjugate addition with organocuprate reagents, and the 1,4-adducts so formed were then readily elaborated to the corresponding 4'-modified aristeromycin analogues. Alternatively, quenching the enolate intermediate of the organocuprate conjugate addition with methanesulfinyl chloride followed by pyrolytic syn elimination resulted in the formation of 4'-modified neplanocin A intermediates. Three of the final compounds (1b, 1c, and 1e) displayed inhibitory activity toward AdoHcy hydrolase in the nanomolar range.

Highly diastereoselective conjugate addition of organocuprate to acyclic E- and Z-enones: Reversal Stereoselectivity under kinetic and thermodynamic conditions

Gilman reagent (lithium dimethylcuprate) adds stereoselectively (98%) to ( E)-and ( Z)-steroidal 22-en-24-ones to yield 22 R-methylated product regardless of the geometry of the enones. The same reagent adds with complete reversal selectivity to the ( E)-and ( Z)-enones in the presence of TMSCl to yield 22 R-and 22 S-methyl-24-ketones, respectively.

Conjugate addition of organocuprates to γ-methyl-δ-oxy-α,β-enones. Influence of the alkoxy substituent on the diastereoselection

The stereochemistry of the conjugate addition of cuprates to the title compounds is mainly governed by the γ-methyl group, but the alkoxy substituent also plays a role. A γ-methyl group exerts the dominant effect in the conjugate addition of a cuprate on a γ-methyl-δ-oxy-α,β-enone, leading to pure anti-addition to the syn substrate, whereas for the anti substrate, a chelating group on oxygen (MEM) definitely assists anti addition. The syn enone reacts exclusively according to the Morokuma model, whereas the anti enone exhibits a chelate effect and fits better with the Isobe model. In both cases, capture of the enolate by iodomethane is stereoselective, so that four contiguous substituted carbons can be created from the initial two, with good stereoselectivity.

Efficient route to the synthesis of C-2, C-3 substituted 4-piperidones

Abstract 1-Carbobenzoxy-3-carbomethoxy-5,6-dihydro-4-pyridone ((1) has proven to be exceptionally receptive in the conjugate addition of organocuprates to give C-2 substituted piperidones having the C-3 position activated toward alkylation. Enone (1) was used as the key synthon in the synthesis of C-1, C-2 and C-3 substituted 4-piperidinol (8).

A practical reversed-polarity alternative to organocuprate conjugate addition chemistry. Halocarbon coupling reactions of enal- and enone-derived allylnickel reagents

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA practical reversed-polarity alternative to organocuprate conjugate addition chemistry. Halocarbon coupling reactions of enal- and enone-derived allylnickel reagentsJohn R. Johnson, Paul S. Tully, Peter B. Mackenzie, and Michal SabatCite this: J. Am. Chem. Soc. 1991, 113, 16, 6172–6177Publication Date (Print):July 1, 1991Publication History Published online1 May 2002Published inissue 1 July 1991https://doi.org/10.1021/ja00016a037RIGHTS & PERMISSIONSArticle Views819Altmetric-Citations61LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (860 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

The conjugate addition of higher-order organocuprates to α-methoxyenones

The conjugate addition of higher-order organocuprates (Lipshutz reagents) at low temperature (−78°C) to α-methoxyenones ( 4) provides the corresponding β-substituted α-methoxy ketones ( 5) in 74-90% isolated yields.

Enantiospecific syntheses of aristeromycin and neplanocin A

The carbocyclic nucleosides (−)-aristeromycin and (−)-neplanocin A were made enantiospecifically in nine steps and ten steps, respectively, from D-ribonic acid γ-lactone. Quenching of an organocuprate conjugate addition reaction with either acetic acid or methanesulfinyl chloride determines whether the divergent synthetic route branches toward (−)-aristeromycin or (−)-neplanocin A

Conjugate reduction of polyfunctional α,β-unsaturated carbonyl compounds using [(Ph 3P)CuH] 6. Compatibility with halogen, sulfonate, and γ-oxygen and sulfur substituents

In contrast to organocuprate conjugate addition and standard methods for conjugate reduction, use of the stable copper(I) hydride cluster, [(Ph 3P)CuH] 6, allows chemoselective conjugate reduction of α,β-unsaturated carbonyl compounds substituted at the γ-position with leaving groups. In addition, the compatibility of the conjugate reduction with organic halides and sulfonate groups is demonstrated.

New copper chemistry. 16. Mechanism of organocuprate conjugate addition: observation of cuprate-olefin complexes and lithium-coordinated intermediates in the reaction of lithium dimethylcuprate(I) with 10-methyl-.DELTA.1,9-2-octalone

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew copper chemistry. 16. Mechanism of organocuprate conjugate addition: observation of cuprate-olefin complexes and lithium-coordinated intermediates in the reaction of lithium dimethylcuprate(I) with 10-methyl-.DELTA.1,9-2-octaloneSteven H. Bertz and Robin A. J. SmithCite this: J. Am. Chem. Soc. 1989, 111, 21, 8276–8277Publication Date (Print):October 1, 1989Publication History Published online1 May 2002Published inissue 1 October 1989https://doi.org/10.1021/ja00203a038RIGHTS & PERMISSIONSArticle Views555Altmetric-Citations75LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (274 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts