Aqueous Wittig Reactions of Aldehydes with In Situ Formed Semistabilized Phosphorus Ylides

The Wittig reactions of three semistabilized phosphorus ylides generated in situ from the corresponding phosphonium salts with aldehydes in water without any organic cosolvent were investigated. Most of the olefination reactions completed within between 5 min and 4.5 h in refluxing water containing 1.5 equiv of LiOH and 1.4 M LiCl to afford the products in 65–100% yields. The E∶Z selectivity depended not only on the substituent attached to the benzene ring of the ylides but also on the substituent bound to the aromatic aldehydes. LiCl promotes the aqueous Wittig reactions and suppresses decomposition of the ylide or the corresponding phosphonium salt.     

Formation of α-hydroxyketones via irregular Wittig reaction

Αddition reactions of (1-methoxyalkyl)triphenylphosphonium ylides, derived from the corresponding Wittig salts and n-BuLi, to aldehydes were investigated. It was revealed that the betaine LiX complexes, the primary adducts, were converted to α-hydroxyketones, prior to the formation of oxaphosphetanes, by addition of aqueous NH₄Cl at low temperature.     

Preparation and properties of some thiouronium fluorenylides and cyclopentadienylides and the attempted preparation of selenouronium and guanidinium fluorenylides

Some stable thiouronium fluorenylides and cyelopentadienylides, prepared by treatment of the corresponding thiouronium salts with non-aqueous base, exist as tautomeric mixtures of the fluorenylide and fluorenylisothiourea, but undergo reactions typical of ylides, e.g. Wittig reactions with aldehydes or nitrosobenzene; a 2,3,4-triphenylcyclopentadienylide gave anomalous products. The ylides also react with acids, alkali, benzyl bromide, and dimethylacetylene dicarboxylate. N,N'-Diphenyl-selenouronium and -guanidinium analogues appear to exist entirely as the non-ylidic tautomers.     

Synthesis and stereoselectivity of a new type of unsaturated phosphonates

A series of unsaturated phosphonates 2, 3, 4 with structures similar to that of abscisic acid (ABA) were synthesized by the Wittig‐Horner reactions of bisphosphonylmethane 1 with β‐substituted propenals, propargyl aldehydes or α,β‐unsaturated methyl ketones. Compounds 5 were prepared by the Michaelis‐Becker reactions of ω‐bromodienes 7 with sodium phosphites. Compounds 7 were obtained by the phase transfer Wittig reactions of ω‐bromobutylphosphonium salt 6 with β‐substituted propenals. The structures of all new compounds prepared were characterized by ¹H NMR, ³¹P NMR, IR spectra, and elemental analysis or MS. The stereochemistry of the Wittig reactions was studied. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:261–266, 2000     

A New Route to Mercury-Containing Triphenylphosphonium Salts with Electron-Withdrawing Groups at the P Atom and Some Transformations of These Compounds

(Aroylmethyl)triphenylphosphonium salts react with mercury(II) trifluoroacetate with replacement of the labile methylene hydrogen atom by the HgOCOCF₃ group to give mercury-containing triphenylphosphonium salts in quantitative yields. Treatment of the mercurated salts with potassium carbonate yields mercury-containing triphenylphosphonium ylides of symmetrical and unsymmetrical structures, which enter Wittig reaction with aromatic aldehydes to form the corresponding mercurated olefins (Z isomers) and triphenylphosphine oxide.     

Wittig and horner-wittig coupling reactions of 2-substituted cyclic ethers and their application to spiroketal synthesis

Wittig and Horner-Wittig coupling reactions of tetrahydropyran or tetrahydrofuran 2-triphenylphosphonium salts or 2-diphenylphosphine oxides with aldehydes and lactols affords good yields of the corresponding enol ethers. In selected examples these enol ether products may be further converted to spiroketals some of which are natural pheromones derived from $\text{Dacus oleae}$ and $\text{Paravespula vulgaris}$.     

Synthesis of dienic fluorinated analogs of insect sex pheromones

Synthesis of fluorinated analogs of some dienic insect sex pherormones through a stereocontrolled Wittig reaction of β-fluorinated aldehydes with the appropriate ω-functionalized ylides is reported. Some features of the ¹H and ¹⁹F NMR spectra of these analogs are also discussed.     

Wittig reactions in water media employing stabilized ylides with aldehydes. Synthesis of alpha,beta-unsaturated esters from mixing aldehydes, alpha-bromoesters, and Ph3P in aqueous NaHCO3

Water is demonstrated to be an effective medium for the Wittig reaction over a wide range of stabilized ylides and aldehydes. Despite sometimes poor solubility of the reactants, good chemical yields normally ranging from 80 to 98% and high E-selectivities (up to 99%) are achieved, and the rate of the reactions in water is unexpectedly accelerated. The efficiency of water as a medium in the Wittig reaction is compared to conventional organic solvents ranging from carbon tetrachloride to methanol. The aqueous Wittig reaction works best when large hydrophobic entities are present, such as aromatic, heterocyclic aromatic carboxaldehydes, and long-chain aliphatic aldehydes with triphenylphosphoranes. The E/Z-isomeric ratio of the Wittig products appears dependent on the electron-accepting/donating capacity and the location of the substituents present in the aromatic ring. The effect of additives, such as benzoic acid, LiCl, and sodium dodecyl sulfate (SDS), on the Wittig reaction has been explored. The Wittig reaction can also be conducted in the presence of acidic entities, such as phenols and carboxylic acids. In addition, large alpha-substituents in the aliphatic aldehydes do not jeopardize the reaction. It is also demonstrated that hydrates of aldehydes can be used directly in the aqueous Wittig reaction as substrates. The scope of the aqueous Wittig reaction is extended to 24 examples of one-pot mixtures of Ph3P, alpha-bromoesters, and aldehydes in sodium bicarbonate solution (at 20 degrees C for 40 min to 3 h) to provide Wittig products of up to 99% yield and up to 98% E-selectivity. Since water is inexpensive, extremely easy to handle, and represents no environmental concerns, it should be considered a possible medium for new organic reactions.     

(Z)-Selective Wittig and Corey-Chaykovsky reactions of propargyl ylides using trialkylgallium bases

Trialkylgalliums deprotonated propargylphosphonium salts and propargylsulfonium salts to form propargyl ylides. The resulted organogallium intermediates underwent the Wittig reaction and the Corey-Chaykovsky reaction with aldehydes giving (Z)-enynes and (Z)-epoxides predominantly. The use of an appropriate trialkylgallium is essential for the stereoselectivity.     

Dipyrazolinyl-substituted 1,4-distyrylbenzenes

A number of dipyrazolinyl-substituted 1,4-distyryl- and 1,4-distyryl-2-methylbenzenes — new luminophores that have intense yellow-green luminescence — were obtained by the Wittig reaction by refluxing 1-(4-formylphenyl)-3-aryl-5-phenyl-2-pyrazolines and aromatic bisphosphonium salts in isopropyl alcohol in the presence of sodium isopropoxide. The low reactivities of the aldehydes used and the predominant formation of trans isomers in the Wittig reaction are noted. Data from the IR and electronic absorption spectra and the fluorescence spectra of the synthesized compounds are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 532–535, April, 1979.     

Studies on the synthesis of 2-(2-arylvinyl)thieno[2,3-d]pyrimidines and 5-(2-arylvinyl)triazolothieno[3,2-e]pyrimidines

Synthesis of 2-(2-arylvinyl)thienopyrimidines, by the acid catalyzed condensation of nitriles with thiophene o-aminocarbonyl compounds, the condensation of aldehydes with thiophene o-aminoamides, the base catalyzed condensation of aldehydes with 2-methylthienopyrimidines and by the Wittig condensation of 2-thieno-pyrimidinylmethylphosphonium salts with aldehydes is described. Isomeric 5-methyltriazolothienopyrimidines were found to react, under basic condition, with aldehydes yielding 5-(2-arylvinyl)triazolo[2,3-c]thieno-pyrimidines. While 5-styryltriazolo[4,3-c] isomers resisted acid catalysed isomerization, they were found to isomerize to triazolo[2,3-c]pyrimidines under base catalysis.     

One‐Pot Wittig Reactions in Aqueous Media: A Rapid and Environmentally Benign Synthesis of α,β‐Unsaturated Carboxylic Esters and Nitriles

One‐pot Wittig reactions of ethyl bromoacetate and bromoacetonitrile with aldehydes in the presence of PPh₃ and LiOH in water were investigated. Most of the olefination reactions completed within 5–120 min in refluxing water containing 1.2 M LiCl to afford the olefin products in 71–97% yields with 100:0–55:45 ratios of E:Z isomers.     

原位生成的烯丙基磷叶立德与醛的化学反应性研究

介绍了我们小组最近有关原位生成的烯丙基磷叶立德与醛的化学反应性研究结果.在化学计量叔膦作用下,烯丙基碳酸酯或联烯酸酯经原位生成的烯丙基磷叶立德活性中间体,与醛发生高度立体选择性的三组分Wittig烯化反应和vinylogous Wittig烯化反应,该类反应为合成多取代1,3-二烯衍生物提供了简单、高效的新方法;在催化量叔膦作用下,γ-甲基联烯酸酯经烯丙基磷叶立德关键中间体与醛发生多个膦催化的环化反应,为五元、六元含氧杂环化合物的合成提供了原子经济性的方法.通过氘代实验和核磁跟踪等方法,对上述反应机理进行了初步探索.     

Wittig reaction with ion-supported Ph3P

Ion-supported Ph₃P, 4-(diphenylphosphino)benzyltrimethylammonium bromide A and N-methyl-N-[4-(diphenylphosphino)benzyl]pyrrolidinium bromide B, were used for the Wittig reaction. Ion-supported phosphonium salts A1 and B1, which were prepared from the reactions of ion-supported Ph₃P A and B with ethyl bromoacetate, respectively, reacted with aromatic and aliphatic aldehydes in the presence of K₂CO₃ to give the corresponding α,β-unsaturated ethyl esters in good yields with high purity by simple filtration of the reaction mixture and subsequent removal of the solvent from the filtrate. Similarly, ion-supported phosphonium salts A2 and B2, which were prepared from the reactions of ion-supported Ph₃P A and B with p-methylbenzyl bromide, respectively, reacted with aromatic and aliphatic aldehydes in the presence of NaH to provide the corresponding p-methylstyrene derivatives in good yields with high purity by simple filtration of the reaction mixture and the subsequent removal of the solvent from the filtrate. In both reactions, the co-product, ion-supported Ph₃PO, could be obtained quantitatively by simple filtration, and was converted into the corresponding ion-supported Ph₃P A and B again in high yields using dimethyl sulfate, followed by the reduction with LiAlH₄. Recovered and regenerated ion-supported Ph₃P A and B could be reused for the same Wittig reaction while maintaining good yields of ethyl (E)-3-(4′-chlorophenyl)-2-propenoate and 1-(4′-chlorophenyl)-2-(4″-methylphenyl)ethene with high purity by simple filtration and removal of the solvent from the filtrate.     

金属化的苄叉基膦叶立德与羰基化合物的Wittig反应的立体化学

首次系统报道了金属化的苄叉二苯基膦烷与芳香醛、酮的Wittig的立体化学，与相应的单叶立德相比，反应具有高的立体选择性、反应活性和较好的原子经济性的优点。     

The dimesitylboron group in organic synthesis 7. A unique variant of the Boron-Wittig reaction which stereoselectively yields 1,2-diols

Low temperature oxidation of the intermediates in the Wittig reactions of aryl aldehydes with carbanions stabilised with an adjacent dimesitylboron group leads stereo-selectively to $\text{erythro}$-1,2-diols. The mechanistic implications for the boron-Wittig reactions are discussed.     

Water is an efficient medium for Wittig reactions employing stabilized ylides and aldehydes

Water is demonstrated to be an excellent medium for the Wittig reaction employing stabilized ylides and aldehydes. Although the solubility in water appears to be an unimportant characteristic in achieving good chemical yields and E/Z-ratios, the rate of Wittig reactions in water is unexpectedly accelerated.     

Preparation of New Wittig Reagents and Their Application to the Synthesis of alpha,beta-Unsaturated Phosphonates

The Wittig reagent [(diethoxyphosphinyl)methylidene]triphenylphosphorane (1b) has been successfully synthesized for the first time via its phosphonium triflate salt (4a), by treating (diethoxyphosphinyl)methyl triflate with triphenylphosphine. The procedure has been applied to the synthesis of other phosphoranes and phosphonium salts. The new Wittig reagents thus synthesized were treated with various aldehydes and an activated ketone, affording the corresponding alpha,beta-unsaturated phosphonates. Triphenylphosphorane 1b and triphenylphosphonium 4a led to both cis and trans isomers with the latter being predominant, while trans isomers were almost exclusively formed when tributyl reagents (1c and 4d) were used.     

Synthesis of Substituted Phosphonates and Their Reactions with Carbonyl Compounds

Abstract

The reaction of the derivatives of 3-phenyl-3-chloro-2-oxopropionic acid with the trivalent phosphorus compounds has been studied. The esterification or amidation of this acid have been shown to influence the course of reaction with Ph₃P. In the reaction with esters enolphosphonium salts are produced, ketophosphonium salts are obtained when amides are involved. Properties of these compounds have also been studied in the Wittig reaction. 3-(α-chlorobenzyl)-2-oxoquinoxaline which reacted with trialkyl phosphates (Arbuzov reaction) has been synthesized. These phosphonates are obtained in nearly quantitative yields, in alkaline conditions (Horner-Emmons reaction) they react smoothly with aromatic aldehydes to give the substituted vinylyuinoxalines.     

Phosphine‐Relayed Aldehyde‐Olefination and Aza‐Wittig Reaction with 2,2,2‐Trifluorodiazoethane

Phosphine‐relayed olefination and aza‐Wittig reactions of readily available aldehydes with 2,2,2‐trifluorodiazoethane (CF₃CHN₂) have been realized. This protocol enables the facile construction of a series of trifluoromethylated alkenes and hydrazones in good to high yield under mild conditions.