Carbon-hydrogen Insertion Reactions Research Articles

ChemInform Abstract: Intramolecular Catalytic Asymmetric Carbon—Hydrogen Insertion Reactions. Synthetic Advantages in Total Synthesis in Comparison with Alternative Approaches.

AbstractReview: 128 refs.

Intramolecular catalytic asymmetric carbon–hydrogen insertion reactions. Synthetic advantages in total synthesis in comparison with alternative approaches

The synthetic potential of highly directional formal insertion of a carbene between carbon and hydrogen of a carbon-hydrogen bond has recently been developed for intramolecular reactions that lead to compounds of biological and medicinal interest. Stereoselective and regiocontrolled intramolecular processes from diazoacetate reactants, catalyzed by dirhodium(II) compounds with chiral carboxamidate ligands, provide efficient and selective access to compounds as diverse as enterolactone, baclofen, imperanene, xylolactone, and rolipram. A comparison of the C-H insertion methodology with alternative approaches is presented.

ChemInform Abstract: Asymmetric Synthesis of Lactones with High Enantioselectivity by Intramolecular Carbon-Hydrogen Insertion Reactions of Alkyl Diazoacetates Catalyzed by Chiral Rhodium(II) Carboxamides.

ChemInform Abstract: Asymmetric Synthesis of Lactones with High Enantioselectivity by Intramolecular Carbon-Hydrogen Insertion Reactions of Alkyl Diazoacetates Catalyzed by Chiral Rhodium(II) Carboxamides.

ChemInform Abstract: Enantioselective Syntheses of 2-Deoxyxylono-1,4-lactone and 2-Deoxyribono-1,4-lactone from 1,3-Dioxan-5-yl Diazoacetates.

1,3-Dioxan-5-yl diazoacetates are valuable substrates for highly diastereoselective and enantioselective carbon-hydrogen insertion reactions. trans-2-(tert-Butyl)-1,3-dioxan-5-yl diazoacetate is a direct precursor to 2-deoxyribono-1,4-lactone in up to 81% ee, whereas cis-2-(tert-butyl)-1,3-dioxan-5-yl diazoacetate yields only the protected 2-deoxyxylono-1,4-lactone in up to 96% ee. However, trans-2-aryl-1,3-dioxan-5-yl diazoacetate (aryl = phenyl or 2-naphthyl) forms the precursor to 2-deoxyxylono-1,4-lactone in up to 95% ee but with the mirror image configuration of that produced from the trans-2-(tert-butyl) analogue. The catalysts that are most suitable for these carbon-hydrogen insertion reactions are chiral dirhodium(II) carboxamidates. 1,3-Dialkoxy-2-propyl diazoacetates give mainly 2-deoxyxylono-1,4-lactone derivatives (>90:10) with generally high enantiocontrol, but replacement of hydrogen at the 2-position of these 2-propyl diazoacetates led to a mixture of products.

Perspective on Dirhodium Carboxamidates as Catalysts

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Perspective on dirhodium carboxamidates as catalysts.

Dirhodium compounds are emerging as highly efficient catalysts for diverse reactions, and those with carboxamidate ligands have the broadest applications. The unique features of these compounds are their structural rigidity, ease of ligand exchange, open diaxial sites for coordination with Lewis bases, and their low oxidation potential. As consequences of this, dirhodium carboxamidates are efficient and effective catalysts for metal carbene reactions, Lewis acid-catalyzed processes, and chemical oxidations. With chiral carboxamidate ligands these dirhodium compounds show exceptional enantiocontrol for intramolecular cyclopropanation and carbon-hydrogen insertion reactions of diazoacetates, and they are also highly efficient and selective for hetero-Diels-Alder reactions. Their limitations lie in their moderate reactivities for metal carbene generation and Lewis acid catalysis and in the cost of the precious metal rhodium.

Chiral Dirhodium(II) Carboxamidates for Asymmetric Cyclopropanation and Carbon—Hydrogen Insertion Reactions

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Amplification of Asymmetric Induction in Sequential Reactions of Bis-diazoacetates Catalyzed by Chiral Dirhodium(II) Carboxamidates

[reaction: see text] Two sequential intramolecular carbon-hydrogen insertion or cyclopropanation reactions of bis-diazoacetates using chiral dirhodium(II) carboxamidate catalysts are reported. The initial metal carbene transformation forms an excess of one enantiomer that with the second transformation further enhances stereocontrol (kinetic amplification). Diastereoselectivity and enantioselectivity for product formation are controlled by the catalyst.

Stereoselectivity in metal carbene and Lewis acid-catalyzed reactions from diastereomeric dirhodium(II) carboxamidates: Menthyl N-acetyl-2-oxoimidazolidine-4( S)-carboxylates

The influence of a chiral menthyl group as the pendant ester substituent on the N-acetyl-2-oxoimidazolidine-4 S-carboxylate ligands in chiral dirhodium(II) imidazolidinone catalysts has been examined. Significant match/mismatch influences are evident in the observed stereocontrol for carbon–hydrogen insertion reactions with diazoacetates, but these effects are minimal in cyclopropanation reactions. Steric restrictions prevent effective enantiocontrol in hetero-Diels–Alder reactions using these menthyl-substituted catalysts.

Catalysts with mixed ligands on immobilized supports. Electronic and steric advantages.

[reaction: see text] Immobilized dirhodium(II) catalysts having mixed chiral ligands enhance reactivity (AH = azetidinone) and influence stereoselectivity in cyclopropanation and carbon-hydrogen insertion reactions.

Total Synthesis of (S)‐(+)‐Imperanene. Effective Use of Regio‐ and Enantioselective Intramolecular Carbon—Hydrogen Insertion Reactions Catalyzed by Chiral Dirhodium(II) Carboxamidates.

The total synthesis of (S)-(+)-imperanene, a natural product found in Chinese medicine, has been completed in 12 steps from a commercially available cinnamic acid. The key step is highly enantioselective carbon-hydrogen insertion from a diazoacetate using a chiral dirhodium(II) carboxamidate catalyst. An elimination process essential to the construction has been optimized to avoid intramolecular Friedel-Crafts alkylation.

Enantioselective carbon-hydrogen insertion is an effective and efficient methodology for the synthesis of (R)-(-)-baclofen.

A highly enantioselective methodology for the synthesis of the GABA(B) receptor agonist (R)-(-)-baclofen is described. This synthesis begins with p-chlorophenethyl alcohol and involves a catalytic carbon-hydrogen insertion reaction of a chiral dirhodium(II) carboxamidate with the corresponding diazoacetate (81% yield, 95% ee). Subsequent steps convert the intermediate gamma-lactone to (R)- (-)-baclofen in a 60% overall yield. The amount of catalyst required for the C-H insertion transformation is only 0.5 mol%.

Highly Selective Synthesis of a 2-Deoxyxylonolactam via Enantioselective Carbon-Hydrogen Insertion Reactions Using Chiral Dirhodium(II) Carboxamidates

Highly Selective Synthesis of a 2-Deoxyxylonolactam via Enantioselective Carbon-Hydrogen Insertion Reactions Using Chiral Dirhodium(II) Carboxamidates

Enantioselective Syntheses of 2-Deoxyxylono-1,4-lactone and 2-Deoxyribono-1,4-lactone from 1,3-Dioxan-5-yl Diazoacetates.

1,3-Dioxan-5-yl diazoacetates are valuable substrates for highly diastereoselective and enantioselective carbon-hydrogen insertion reactions. trans-2-(tert-Butyl)-1,3-dioxan-5-yl diazoacetate is a direct precursor to 2-deoxyribono-1,4-lactone in up to 81% ee, whereas cis-2-(tert-butyl)-1,3-dioxan-5-yl diazoacetate yields only the protected 2-deoxyxylono-1,4-lactone in up to 96% ee. However, trans-2-aryl-1,3-dioxan-5-yl diazoacetate (aryl = phenyl or 2-naphthyl) forms the precursor to 2-deoxyxylono-1,4-lactone in up to 95% ee but with the mirror image configuration of that produced from the trans-2-(tert-butyl) analogue. The catalysts that are most suitable for these carbon-hydrogen insertion reactions are chiral dirhodium(II) carboxamidates. 1,3-Dialkoxy-2-propyl diazoacetates give mainly 2-deoxyxylono-1,4-lactone derivatives (>90:10) with generally high enantiocontrol, but replacement of hydrogen at the 2-position of these 2-propyl diazoacetates led to a mixture of products.

Synthesis of pyrrolizidine bases by highly diastereoselective and regioselective catalytic carbon-hydrogen insertion reactions of chiral pyrrolidinediazoacetamides

Pyrrolizidines, (1S, 8S)-1-hydroxypyrrolizidin-3-one and (−)-heliotridane, have been prepared in high yield from diazoacetamides of 2-substituted-pyrrolidines by carbon-hydrogen insertion catalyzed by dirhodium(II) tetrakis[methyl 1-acylmidazolidin-2-one-4(S)-carboxylates].

Enhancement of enantiocontrol/diastereocontrol in catalytic intramolecular cyclopropanation and carbon-hydrogen insertion reactions of diazoacetates with Rh2(4S-MPPIM)4

Summary Dirhodium(II) tetrakis[methyl 1-(3-phenylpropanoyl)imidazolidin-2-one-4(S)-carboxylate], Rh 2 (4S-MPPIM) 4 , provides significant enhancement in enantiocontrol for intramolecular cyclopropanation reactions of allylic diazoacetates and optimal enantiocontrol/diastereocontrol for intramolecular C-H insertion reactions of secondary alkyl diazoacetates.

Enantiomer differentiation in intramolecular carbon?hydrogen insertion reactions of racemic secondary alkyl diazoacetates catalyzed by chiral dirhodium(ii) carboxamidates

Highly efficient kinetic resolution of racemic secondary alkyl diazoacetates in intramolecular carbon-hydrogen insertion reactions has been achieved using chiral dirhodium(ii) carboxamidates. Products formed from catalytic diazo decomposition of racemic 2-octyl diazoacetate and, separately, its (2R)- and (2S)-enantiomeric forms, as well as bothcis- andtrans-2-methylcyclohexyl diazoacetates, have been systematically evaluated. Enantioselectivities up to 99 %ee have been obtained for γ-lactone formation. β-Lactone production has been observed and, although minor with cyclohexyl diazoacetates, is the major insertion pathway for diazo decomposition of 2-octyl diazoacetate.

Improved enantioselection for chiral dirhodium(II) carboxamide-catalysed carbon-hydrogen insertion reactions of tertiary alkyl diazoacetates

Improved enantioselection for chiral dirhodium(II) carboxamide-catalysed carbon-hydrogen insertion reactions of tertiary alkyl diazoacetates

Improved enantioselection for chiral dirhodium(II) carboxamide-catalysed carbon-hydrogen insertion reactions of tertiary alkyl diazoacetates

Enantiocontrol in CH insertion reactions of 3° alkyl diazoacetates, which is highly dependent on the catalyst ligand, is greatly enhanced with the use of dirhodium(II) tetrakis[methyl 1-acetylimidazolidin-2-one-4(S)-carboxylate], Rh 2(4S-MACIM) 4.

Enantioselective Synthesis of a 1,2-Disubstituted Mitosene by a Copper-Catalyzed Intramolecular Carbon-Hydrogen Insertion Reaction of a Diazo Ester

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnantioselective Synthesis of a 1,2-Disubstituted Mitosene by a Copper-Catalyzed Intramolecular Carbon-Hydrogen Insertion Reaction of a Diazo EsterHee-Jong Lim and Gary A. SulikowskiCite this: J. Org. Chem. 1995, 60, 8, 2326–2327Publication Date (Print):April 1, 1995Publication History Published online1 May 2002Published inissue 1 April 1995https://doi.org/10.1021/jo00113a008RIGHTS & PERMISSIONSArticle Views570Altmetric-Citations57LEARN 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 (299 KB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts