An Efficient Synthesis of Stable Phosphorus Ylides Derived from Triphenylphosphine,Dialkyl Acetylenedicarboxylates,and an NH-Acid

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH-acids, such as benzotriazole, 5-methylbenzotriazole, 5-chlorobenzotriazole, pyrrole, 2-acetylpyrrole, pyrrole-2-carboxaldehyde, 4-nitro-acetanilide, 4-methoxyacetanilide, 4-bromoacetanilide, 4-methylacetanilide, 2-methyl-acetanilide, and 2,6-dimethylacetanilide. These stable ylides exist in a solution as a mixture of two geometrical isomers as a result of the restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

A Simple Synthesis of Stable Phosphorus Ylides from Indole and Some of Its Derivatives

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH acids, such as indole and 2-methyl indole, 3-methyl indole, and 5-boromo indole. These stable ylides exist in a solution as a mixture of two geometrical isomers as a result of the restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

Indole- and pyrrole-sulfonium ylides

Electrophilic substitution of indole and pyrrole with sulfoxides and acid anhydrides leads to the formation of indole-3-sulfonium salts and pyrrole-2-sulfonium salts. These are deprotonated with potassium carbonate to give indole-3-sulfonium ylides and pyrrole-2-sulfonium ylides. An indole-2-sulfonium ylide was obtained by methylation and subsequent deprotonation of 2-(methylthiol)indole.     

Pt(II)- or Au(III)-catalyzed [3+2] cycloaddition of metal-containing azomethine ylides: highly efficient synthesis of the mitosene skeleton

[reaction: see text] Only 1-3 mol % of PtCl(2) or AuBr(3) was sufficient to promote generation and [3+2] cycloaddition of transition-metal-containing azomethine ylides derived from N-(o-alkynylphenyl)imines bearing an internal alkyne moiety. A highly efficient method for the preparation of synthetically useful tricyclic indole derivatives having a substituent at the 3-position of the indole nucleus was established by this method.     

Synthesis of chalcone analogs -4- and 5-nitropyrrole derivatives

Nitropyrrole analogs of chalcone have been synthesized by aldol condensation in basic medium from 5-nitropyrrole-2-carboxaldehyde, 4- and 5-nitro-2-acetylpyrrole, and the corresponding aromatic aldehydes and methyl ketones; their 2, 4-dinitrophenylhydrazones have been obtained. Some considerations are expressed concerning the reactivity of pyrrole-2-carboxaldehyde, 2-acetylpyrrole, and their nitro derivatives.     

Synthesis and dynamic 1H NMR study around the carbon–carbon double bond in the new stable phosphorus ylides derived from the reaction between hexamethyl phosphorous triamide and dimethyl acetylenedicarboxylate in the presence of NH‐heterocyclic compounds

New and stable phosphorous ylides are obtained from a simple and efficient one‐pot three‐component reaction between hexamethyl phosphorous triamide and dimethyl acetylenedicarboxylate in the presence of NH‐heterocyclic compounds in excellent yields at an ambient temperature. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of the restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group. Dynamic effects are observed in the ¹H NMR spectra that are attributed to the restricted rotation around the carbon–carbon double bond. The experimental rotational energy barrier (Δ G^#) and other activation parameters on the basis of the ¹H NMR study for the rotational interchangeable process of major and minor isomers in ylides 4a–d are reported. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:131–137, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20761     

Synthesis of benz[5,6]azepino[4,3-b]indoles by 1,7-electrocyclisation of azomethine ylides

A new, general route to the benz[5,6]azepino[4,3-b]indole ring system has been developed via the 1,7-dipolar electrocyclisation reactions of azomethine ylides derived from easily available 3-formyl indole derivatives. The intermediacy of azomethine ylides was shown by the trapping of the proposed α,β:γ,δ-conjugated dipole with N-phenylmaleimide.     

NMR study,theoretical calculations for assignment of the Z‐ and E‐isomers,and kinetics investigation of stable phosphorus ylides involving a 2‐mercapto‐4,6‐dimethyl pyrimidine

In the present work, NMR, theoretical, kinetics, and mechanism investigations were undertaken for a one‐pot condensation reaction between 2‐mercapto‐4,6‐dimethyl pyrimidine and dialkyl acetylenedicarboxylates in the presence of triphenyphosphine containing novel stable phosphorus ylides 4a–c . Herein, theoretical calculations have been employed for assignment of the most stable isomers (Z or E) of phosphorus ylides 4a,c by natural population analysis, atoms in molecules methods, and CHelpG keyword, in which E‐ 4(a, c) are more stable forms as the majors. The ¹H, ¹³C, and ³¹P NMR data of these ylides are consistent with results obtained from theoretical calculations. In addition, kinetic investigation of new ylides was undertaken by ultraviolet spectrophotometry. Useful information was obtained from studies of the effect of solvent, structure of reactants (different alkyl groups within the dialkyl acetylenedicarboxylates), and also the concentration of reactants on the rate of reactions. The proposed mechanism was confirmed according to the obtained results and a steady‐state approximation, and the first step (k₂) of the reaction was recognized as a rate‐determining step on the basis of the experimental data. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:462–474, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20632     

Simple Synthesis of Stable Phosphorus Ylides Derived from Imidazolidine-2-Thione. Efficient One-Pot Synthesis of α-Amino Esters with β-Phosphorus Substituents

Crystalline phosphorus ylides are obtained in nearly quantitative yields from the addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and imidazolidine-2-thione. A dynamic NMR effect is observed in the ¹ H NMR spectrum of the stabilized ylide obtained from dimethyl acetylenedicarboxylate (Δ G ^≠ = 66.6 kJmol^?1 ) and is attributed to restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

Regioselective synthesis of mono- and bis-decahydrobenzocarbazoles via tandem reactions of α-diazo ketones

Regioselective intermolecular 1,3-dipolar cycloaddition reactions of rhodium generated carbonyl ylides with indoles are reported in this paper. Intermolecular 1,3-dipolar cycloaddition reactions of five-membered-ring cyclic carbonyl ylides with indole and substituted indoles afforded hexahydro-2H-carbazol-2-ones in a regioselective manner. Similarly, reactions of cyclic carbonyl ylides were carried out to afford decahydrobenzo[c]carbazoles or decahydrocyclopenta[c]carbazoles with high regioselectivity. Interestingly, the other possible regioisomer decahydrobenzo[a]carbazoles were also obtained by the reaction of cyclic carbonyl ylides and indoles having electron withdrawing substituents. The structure and stereochemistry of regioisomers 6,11c-epoxy-1,2,3,4,4a,5,6,6a,11b,11c-decahydro-4a-methyl-5-oxo-7H-benzo[c]carbazole and 11-benzenesulfonyl-6,11b-epoxy-2,3,4,4a,5,6,6a,11,11a,11b-decahydro-4a-methyl-5-oxo-1H-benzo[a]carbazole were unequivocally corroborated by single-crystal X-ray analyses. To advance this study, regioselective double 1,3-dipolar cycloaddition reaction of five-membered-ring cyclic carbonyl ylides has been demonstrated for the first time with biindoles having various aryl and alkyl spacers. This process constructed up to eight stereocenters, four carbon-carbon and two carbon-oxygen bonds in a single step with an excellent molecular complexity and stereoselectivity.     

有机胂化合物的研究 Ⅵ.胂叶立德与异氰酸苯酯的反应

本文报道稳定胂叶立德与异氰酸苯酯反应时,在胂叶立德的亚甲基碳原子上发生N-苯胺甲酰化,并得到相应的稳定双羰基胂叶立德。经元素分析,IR和~1HNMR鉴定,确证了产物的结构。     

Electrochemical oxidation of substituted pyrroles. III. Anodic oxidation of 2,5-diphenyl-3-acetylpyrrole

The electrochemical oxidation of 2,5-diphenyl-3-acetylpyrrole (I) is described. The cyclic derivative 1,6a-dihydro-2,5,6a-triphenyl-3,4-diacetylbenzo[g]pyrrolo[3,2-e]indole (II) was obtained in very good yield. However, when water was present in the reaction medium, a different derivative, 4-acetyl-2-hydroxy-2,5-diphenyl-3-(4′-acetyl-2′,5′-diphenyl-3′-yl)-2H-pyrrole (III) , was obtained as the main product. 2,2′,5,5′-Tetraphenyl-4,4′-diacetyl-3,3′-dipyrryl (IV) , a potentially useful intermediate for the synthesis of condensed pyrroles, was synthesized by zinc reduction of III.     

Synthesis of tetracyclic indole-containing ring systems by intramolecular cycloadditions of azomethine ylides

Dipolar cycloaddition of azomethine ylides derived from addition of amines to a 2-butenylindole-3-carboxaldehyde provides a stereoselective synthesis of tetracyclic products present in a variety of indole alkaloids. The chemistry was applied to a formal synthesis of the iboga alkaloid deethylibophyllidine.     

An Efficient One-Pot Synthesis of 2,3-Dialkyl-1,1-Diethyl-1-(Acetylamino)-3-(1,1,1-Triphenylphosphanilidene)-1,1,2,3-Propanetetracarboxylates and Their Temperature-Dependent NMR Spectra

Abstract

Stable crystalline phosphorus ylides of 1,1-diethyl 2,3-dimethyl 1-(acetylamino)-3-(1,1,1-triphenylphosphanilidine)-1,1,2,3-propanetetracarboxylates were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of diethyl acetamidomalonate as a CH-acid. These stable ylides exist in solution as a mixture of two geometrical isomers (E and Z) as a result of restricted rotation around the carbon–carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group on the nuclear magnetic resonance (NMR) time scale at ambient temperature. The dynamic effects in the ylide moieties were investigated by ¹H NMR spectra.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Rhodium(III)-catalyzed intermolecular cyclization of anilines with sulfoxonium ylides toward indoles

C2-substituted indoles were efficiently prepared with excellent regio-selectivity from N-phenylpyridin-2-amines and sulfoxonium ylides via cascade reaction of C-H alkylation/nucleophilic cyclization.     

Revidierte Struktur von Verrucarin E. Eine Synthese des Antibioticums und verwandter β-Acetyl-Pyrrol-Derivate. Verrucarine und Roridine, 18. Mitteilung [1]

The structure of Verrucarin E, an antibiotic isolated from Myrothecium verrucaria, has been corrected (cf. [4]) and shown to be that of 3-acetyl-4-hydroxymethyl-pyrrole ( 2 ) by comparison with a variety of β-acetylpyrrole-derivatives, whose NMR. chemical shifts and coupling constants are reported. Verrucarin E ( 2 ) has been synthesized in low yield from 3-acetylpyrrole ( 12 ). The following previously unknown β-acetylpyrrole-derivatives are described: 3-acetyl-5-methyl-pyrrole-2-carbonic-acid ( 11 ), 4-acetyl-2-methyl-pyrrole ( 13 ), 3-acetyl-4-formyl-pyrrole ( 7 ), 3-acetyl-1-hydroxymethyl-pyrrole ( 14 ), 3-(3-hydroxypropionyl)-pyrrole ( 15 ), 3-(3-hydroxy-2-hydroxymethyl-propionyl)-pyrrole ( 16 ), and 3-(3-acetyl-pyrr-1-yl)-1-(pyrr-3-yl)-propan-1-one ( 17 ).     

Regioselective and Stereoselective Addition of Tetrazole Derivatives to Electron‐poor Acetylenic Esters in the Presence of Triphenylphosphine

Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and acetylenic esters by tetrazole derivatives leads to the formation of vinyltriphenylphosphonium salts. The cation of these salts undergoes an addition reaction with the counter anion in CH₂Cl₂ at room temperature to yield the corresponding stabilized phosphorus ylides. Elimination of triphenylphosphine from the stabilized phosphorus ylides leads to the corresponding electron‐poor N‐vinyl tetrazoles in fairly high yields. Structures of N‐vinyl tetrazoles were determined by IR, ¹H NMR, ¹³C NMR and single crystal X‐ray structure analyses. The reaction is fairly regioselective and stereoselective.     

非稳定型亚甲胺基叶立德参与的三组分1,3-偶极环加成反应合成新型四氢吡咯衍生物

N-三甲基硅甲基苄胺和多聚甲醛在磷酸催化下生成非稳定型亚甲胺基叶立德,继而与各种贫电子烯烃在温和条件下发生三组分1,3-偶极环加成反应,高收率合成了10个3,4-二取代四氢吡咯衍生物(其中6个为新化合物),其结构经1H NMR,13C NMR和HR-MS表征。     

Studies on ylides: exclusive carbonyl olefination with semistabilized arsonium ylides

The reactions of some semistabilized arsonium ylides with 9-anthrones and 9-anthraldehyde give 9-arylidene-10-hydroanthracenes, 9-arylidene-2-chloro-10-hydroanthracenes and 1-aryl-2-(9-anthryl)ethylenes, respectively. IR and NMR spectral data of the products are reported.     

NOTE: SYNTHESIS OF Cu(II) AND Zn(II) COMPLEXES WITH SCHIFF BASE DERIVATIVES OF 2-ACETYLPYRROLE

Abstract

Bis chelate complexes of Cu(II) and Zn(II) were synthesized with methylamine and ethylamine Schiff base derivatiies of 2-acetylpyrrole. Stable complexes were obtained, with the exception of the Cu(II) ethylamine adduct. which slowly hydrolyzed in air to yield a mixed ligand product containing one ethylamine Schiff base and one 2-acetylpyrrole per metal centre. The instability of the bis Cu(II) ethylamine Schiff base complex with respect to stable Cu(II) methylamine and Zn(1I) ethylamine complexes is discussed.