Wittig-type Reaction Research Articles

Intramolecular asymmetric olefination of binaphthyl phosphonate derivatives of 1,3-diketones

Intramolecular asymmetric Wittig-type reactions of some chiral binaphthyl phosphonates of 2,2-disubstituted 1,3-dicarbonyl derivatives were investigated. The base-mediated cyclization occurred with differentiation of two diastereotopic carbonyl groups to give non-racemic dihydronaphthalene derivatives with moderate to good enantiomeric excess. The degree of asymmetric induction depended upon the substrates and the best result was obtained with the indanedione derivatives having alkyl substituents in 58–73% yield with 82–88% e.e. The absolute structure of one of the products was unambiguously determined by X-ray analysis and some mechanistic consideration is also given.

Wittig-type olefination catalyzed by PEG-telluride.

Soluble poly(ethylene glycol) (PEG)-supported telluride 2 was designed and synthesized for catalytic Wittig-type reactions. It was found that the catalytic loading could be reduced from 20 to 2 mol % by the introduction of PEG (even to 0.5 mol % when some telluride salts were used as the catalyst). Under the catalytic reaction conditions, a wide variety of aldehydes with different structures could react with bromoacetate to afford beta-substituted or alpha,beta-disubstituted unsaturated esters in high yields with excellent E-stereoselectivity. The modified process, by using sodium bisulfite instead of triphenyl phosphite, represented a very simple product isolation procedure. The roles of PEG for promoting the ylide formation and stabilizing the catalytic species were disclosed. The mechanism was also studied.

Highly Z-Selective Synthesis of Disubstituted α,β-Unsaturated Cyanides and Amides Using 10-P-5 Wittig Type Reagents

Abstract Phosphoranes (10-P-5) bearing cyanomethyl, acetamide, and N,N-dimethylacetamide groups were examined for Wittig type reactions. All three reacted to give the corresponding olefins. The reaction of the cyanomethyl reagent with aldehydes gave α,β-unsaturated cyanides with high Z-selectivity in the case of aliphatic aldehydes (Z:E=94:6 to 99:1). On the other hand, the reactions of the two amide reagents with aldehydes yielded α,β-unsaturated amides with high Z-selectivity for both aromatic and aliphatic aldehydes (Z:E=99:1 to >99:<1).

Novel results obtained by freezing berry pseudorotation of phosphoranes (10‐P‐5)

AbstractBy freezing Berry pseudorotation of spirophosphoranes with recourse to the rigidity of the Martin bidentate ligand, we successfully prepared configurationally stable enantiomeric pairs of optically active phosphoranes, and could isolate “anti‐apicophilic” C‐apical O‐equatorial (O‐cis) phosphoranes. The effect of σ*PO orbital of the O‐cis phosphorane was investigated both experimentally and theoretically. O‐cis phosphoranes were revealed to be much more electrophilic at the phosphorus atom than O‐trans isomers by experimental studies. The acidity of the α‐proton of an O‐cis benzylphosphorane was found to be higher than that of the corresponding O‐trans isomer. By the reaction of the α‐carbanion of an O‐cis benzylphosphorane with PhCHO, we succeeded in the first isolation and full structural characterization of a 12‐P‐6 phosphate bearing an oxaphosphetane ring, the intermediate in the Wittig type reaction using a 10‐P‐5 phosphorane. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:390–396, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10072

Ruthenium-catalyzed two-component addition to form 1,3-dienes: optimization, scope, applications, and mechanism.

A two component coupling of an allene and an activated olefin to form 1,3-dienes has been developed. The requisite allenes are synthesized either from terminal alkynes by a one carbon homologation using copper(I) iodide, paraformaldehyde, and diisopropylamine, via an ortho ester-Claisen rearrangement from a propargylic alcohol, or via a Wittig type reaction on a ketene generated in situ from an acid chloride. Mono- through tetrasubstituted allenes could be synthesized by these methods. Either cyclopentadienylruthenium(II) cyclooctadiene chloride or cyclopentadienylruthenium(II) trisacetonitrile hexafluorophosphate catalyze the addition reaction. When the former catalyst is employed, an alkyne activator is added to help generate the active catalyst. Through systematic optimization studies, a range of conditions was examined. The optimal conditions consisted of the use of cerium(III) trichloride heptahydrate as a cocatalyst in dimethylformamide as a solvent at 60 degrees C. The reaction was found to be chemoselective, and a wide range of functionality was tolerated, including esters, alcohols, nitriles, and amides. When substituted allenes are used, good selectivity can be obtained with proper substitution. A mechanism involving a ruthenacycle is proposed to account for the selectivity or lack thereof in product formation. With disubstituted allenes, selectivity is obtained when beta-hydrogen elimination is favored from a specific site. In tri- and tetrasubstituted allenes, steric issues concerning the C-C bond forming event appear to be the dominant factor in determining product formation. This process represents a highly atom-economical synthesis of 1,3-dienes in a controlled fashion. The utility of the 1,3-diene products was demonstrated by their use in Diels-Alder reactions to form a variety of cyclic systems including polycyclic structures. This sequence represents a convergent atom economic method for ring formation by a series of simple additions.

Reactions of aldehydes with polymer-supported selenoalkylidenetriphenylphosphoranes. A facile method for the synthesis of carbonyl compounds

The transylidation reactions of polymer-bound selenium bromide with alkylidenetriphenylphosphoranes 1 gave resin 2 , which is sufficiently reactive to undergo Wittig-type reactions to afford the vinylic selenide resins 3 . Cleavage gave ketones and aldehydes under different conditions.

A novel three-component butenolide synthesis.

[reaction: see text]. 5-Acylamino butenolides can be assembled by a multicomponent reaction (MCR) of isocyanides, glyoxals, and acetophosphonic acid diethylesters, followed by a intramolecular Wittig-type reaction. The reaction can be performed either in one pot or with the isolation of the intermediate Passerini product. This versatile reaction offers three independent inputs displayed in the final product. Applications in combinatorial chemistry and natural product synthesis can be envisioned.

A Convenient Synthesis of Phenyl 1-Chloro-1 Alkenyl Chalcogenides by One-Pot Wittig Reaction. Synthesis of Selenolesters

The preparation of 1-chloro-1-chalcogeno(sulfur, selenium) alkenes by a Wittig-type reaction in an one pot procedure is described. Chlorochalcogenyl triphenylphosphoranes are formed in situ by the reaction of dichloromethyl phenylchalcogenide, potassium t-butoxide and triphenylphosphine. They react with aldehydes to give 1-chlorovinyl chalcogenides as a mixture of isomers.

Synthesis of α-phenylseleno-α,β-unsaturated esters by Wittig-type reactions. Studies on the Diels–Alder reaction

Ethyl α-phenylseleno-α,β-unsaturated esters were prepared by the reaction of tri-ethyl phosphonoacetate anion and ethoxycarbonyl(phenylselenenyl)methylidene(triphenyl)phosphorane with aliphatic and aromatic aldehydes. The α-phenylseleno unsaturated esters were obtained as mixtures of E/ Z-isomers in medium to good yields and in moderate yields, respectively. α-Phenylselenenyl acrylate was used as dienophile in a Diels–Alder reaction. On reaction with isoprene only the para isomer was obtained while reaction with cyclopentadiene gave a 1:1 mixture of exo/ endo isomers in good yield.

A new synthetic route to TTF-vinylogues

The known method for the syntheses of TTF-vinylogues based on the Wittig-type reaction includes multi-step syntheses of the starting materials. We have developed a new and simple method for the synthesis of TTF-vinylogues. This reaction proceeds smoothly regardless of the substituent and the total number of the reaction steps is remarkably reduced.

A practical catalytic Wittig-type reaction

Download options Please wait... Article information DOI https://doi.org/10.1039/B104100M Article type Communication Submitted 09 May 2001 Accepted 12 Jun 2001 First published 09 Jul 2001 Download Citation Chem. Commun., 2001, 1384-1385 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions A practical catalytic Wittig-type reaction Z. Huang, S. Ye, W. Xia and Y. Tang, Chem. Commun., 2001, 1384 DOI: 10.1039/B104100M To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Zheng-Zheng Huang Song Ye Wei Xia Yong Tang

Gold(I) complexes containing the cationic ylide ligand bis(methyldiphenylphosphonio)methylide

The ylide Ph 2PCHPPh 2Me can be selectively P-alkylated by MeI or MeO 3SCF 3 to form the bis(methyldiphenylphosphonio)methylide salts [MePPh 2CHPPh 2Me]A (AI ( 1), CF 3SO 3 ( 2)). The ylidic carbon shows a weak nucleophilicity and does not give typical reactions with common organic electrophiles, including Wittig type reactions, but it is able to displace tetrahydrothiophene in [AuX(tht)] to give the corresponding C-coordinated gold(I) compounds [Au{CH(PPh 2Me) 2}X]CF 3SO 3 (XCl ( 3), C 6F 5 ( 4)). The crystal structure of ( 4) displays a linear coordination for the gold atom, single PC bond lengths and a PCP angle of 119.1(3)° for the ligand.

A short-step synthesis of orally active carbapenem antibiotic CS-834.

An orally bioavailable carbapenem CS-834, which is a pivaloyloxymethyl (POM) ester-type prodrug and has (R)-5-oxopyrrolidin-3-ylthio moiety at the C-2 position of the 1 beta-methylcarbapenem skeleton, is currently under clinical trial. We accomplished a short-step synthesis of CS-834 by using phosphorus ylide from the intramolecular Wittig-type reaction in the key step for cyclization to the bicyclic carbapenem system. The POM ester group was found to be suitable for the cyclization conditions.

Synthesis of α-Phenylthioacylmethylene Triphenylarsoranes and their Wittig-type Reactions

α-Phenylthio acylmethylene triphenylarsoranes, the first stable α-thiyl arsonium ylides, are prepared by phenylsulfenylation–transylidation reaction of the corresponding acylmethylene triphenylarsoranes with phenylsulfenyl chloride; Wittig reactions are carried out under mild reaction conditions on the arsonium ylides to provide α-phenylthio-α,β-unsaturated ketones.

Synthesis of α-Phenylthioacylmethylene Triphenylarsoranes and their Wittig-type Reactions

α-Phenylthio acylmethylene triphenylarsoranes, the first stable α-thiyl arsonium ylides, are prepared by phenylsulfenylation–transylidation reaction of the corresponding acylmethylene triphenylarsoranes with phenylsulfenyl chloride; Wittig reactions are carried out under mild reaction conditions on the arsonium ylides to provide α-phenylthio-α,β-unsaturated ketones.

Enantiospecific synthesis of α-amino acid semialdehydes: a key step for the synthesis of unnatural unsaturated and saturated α-amino acids

The enantiospecific synthesis of unnatural unsaturated and saturated α-amino acids based on a Wittig type reaction is described. The versatile synthetic intermediates, l-glutamic and l-aspartic acid semialdehydes, are obtained from the corresponding N, N-di-Boc-diesters, by the selective reduction of the ω-ester with DIBAL ® under controlled conditions. The semialdehydes are chemically stable for a prolonged time and react with various phosphorous ylides, under controlled conditions, to produce the enantiomerically pure unsaturated α-amino acids in high yields. The method is equally applicable to homologated diesters obtained by the presented methodology providing unsaturated amino acids with variable unsaturated positions and geometries. The corresponding saturated products can be obtained by simple hydrogenation.

Phase transfer Wittig reaction with 1,3-dioxolan-2-yl-methyltriphenyl phosphonium salts: An efficient method for vinylogation of aromatic aldehydes

Aldehydes were efficiently transformed into allylic dioxolanes by a Wittig-type reaction, using 1,3-dioxolan-2-yl-methyltriphenylphosphonium bromide under phase transfer conditions. The substituent kinetic effects were studied, and related to Hammett values and electrochemical potentials.

A Simplified Preparation of Vinyl Sulfides, Selenides and Tellurides by a Wittig-Type Reaction

A Simplified Preparation of Vinyl Sulfides, Selenides and Tellurides by a Wittig-Type Reaction

Bis(arylidene)tetrathiapentalenes — novel building blocks for extended tetrathiafulvalenes and conducting polymers

1,3,4,6-tetrathiapentalene-2,5-dione (1) undergoes a Wittig-type reaction with aromatic aldehydes 2a - f in neat triethyl phosphite to furnish the novel, disubstituted tetrathiapentalene derivatives ( 3a - f ). Their electrochemical behaviour and donor properties are discussed.

Selective Azide Oxidation of 1,2-Bis(diphenylphosphino)benzene and Related Ethylenebis(phosphines) to Asymmetric Multifunctional Phosphorus Ligands and Formation of Rhodium(I) Complexes of These Ligands. Structural Characterization of the Prototypical Ligand 1-(((Trimethylsilyl)imino)diphenylphosphorano)-2-(diphenylphosphino)benzene and Its Rhodium(I) Complex: 1-Ph(2)P=N(SiMe(3))C(6)H(4)-2-(Ph(2)P)Rh(CO)Cl.

Selective azide mono-oxidation of o-bis(phosphines) such as o-bis(diphenylphosphino)benzene and other bis(phosphines) with cis-substituents on a rigid backbone such as an ethylene structure occurs as the result of the steric control exerted during the azide oxidation (Staudinger) reaction process. The azides used were the trimethylsilyl, 4-cyanotetrafluorophenyl, benzyl, and diphenoxyphosphonyl azides. The prototypical ligand 1-Ph(2)P=N(SiMe(3))-2-(Ph(2)P)C(6)H(4), 2, has been structurally characterized. Crystal data for 2: crystal dimensions, 0.38 x 0.38 x 0.57 mm; space group, monoclinic, P2(1)/c, (No. 14); a = 11.093(5) Å, b = 14.898(5) Å, c = 18.811(2) Å, beta = 102.76(2) degrees, V = 3031 Å(3), Z = 4. Final R, R(w) and GOF values were 0.068, 0.074, and 1.92 respectively. The P=N-SiMe(3) angle was wide, 152.7(3) degrees, and the P=N bond length short (1.529(5) Å) relative to arylated iminophosphoranes but in keeping with the trends for silylated analogs. The iminophosphorane center can be selectively transformed with other agents in a Wittig type reaction converting the azides to the monooxide, monosulfide, etc. The iminophosphoranophosphines are also good complexing agents and the Rh(I) complex derived from 2, 1-Ph(2)P=N(SiMe(3))-C(6)H(4)-2-(Ph(2)P)Rh(CO)Cl, 15 was structurally characterized. Crystal data for 15: crystal dimensions, 0.32 x 0.44 x 0.66 mm; space group, monoclinic, P2(1)/c (No. 14); a = 13.793(3) Å, b = 12.622(11) Å, c = 20.436(6) Å, beta = 105.93(2) degrees, V = 3421.2 Å(3), Z = 4. Final R, R(w), and GOF values were 0.064, 0.061, and 1.45 respectively. The complex shows typical square planar geometry about Rh, a cis phosphine-CO relationship, and no exceptional steric crowding of the coordination site.