Synthesis of Some [1,3]Benzodioxoles via the Reaction of o-Quinones with Phosphorus Ylides

3,5-Di(tert-butyl)benzo-1,2-quinone 1c, phenanthrene-9,10-quinone 11, and 1,2-naphthoquinone 18 react with 1-phenylethylidene(tri-phenyl)phosphorane 2j, cyclopentylidene(triphenyl)phosphorane 2k, cyclohexylidene(triphenyl)phosphorane 2l, and tetrahydro-2-furanyl-methylidene(triphenyl)phosphorane 8 to give the corresponding 2-substituted [1,3]benzodioxoles 5–7, 10, 12–14, 20–22 in low to high yields, instead of Wittig products, with exception of 11,12-dihydro-10H-cyclopenta[b]phenanthro[9,10-d]furan 17. A possible explanation for these reaction sequences is discussed.

     

Comparative Studies on the Behavior of 3-Amino-2-phenyl-4(3 H )-quinazolinone Towards Some Organophosphorus Reagents

The reaction of 3-amino-2-phenyl-4(3H)-quinazolinone with oxovinylidenetriphenylphosphorane afforded 5-phenylpyrazolo[1,5-c] quinazoline-2(3H)-one and triphenylphosphine oxide. On the other hand, when quinazolinone reacts with phosphorus ylides, the corresponding phosphorane adducts were obtained. Moreover, quinazolinone reacts with trisdialkylaminophosphines to give the new (dialkylamino)oxophosphonium dipolar products. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results.     

Comparative Studies on the Behavior of 3-Amino-2-phenyl-4(3<Emphasis Type="Italic">H</Emphasis>)-quinazolinone Towards Some Organophosphorus Reagents

Summary. The reaction of 3-amino-2-phenyl-4(3H)-quinazolinone with oxovinylidenetriphenylphosphorane afforded 5-phenylpyrazolo[1,5-c] quinazoline-2(3H)-one and triphenylphosphine oxide. On the other hand, when quinazolinone reacts with phosphorus ylides, the corresponding phosphorane adducts were obtained. Moreover, quinazolinone reacts with trisdialkylaminophosphines to give the new (dialkylamino)oxophosphonium dipolar products. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results.     

Preparation of Novel Polyoxo Ylides and Diylides and Their Behaviour Towards Pyrolysis and Oxidation

Abstract

We recently reported the preparation of the new trioxoylides 1 and their pyrolysis to give symmetrical diacylalkynes.¹ Reaction of acyl ylides with oxalyl chloride gkes the tetraoxo diylides 2 as shown. The corresponding reactions starting from the α-oxoacyl ylides have been used to obtain examples of tetraoxo ylides 3 and hexaoxo diylides 4.     

The Effect of Very Bulky Groups on the Equilibrium of Penta- and Hexacoordinated Phosphoranes 1

The synthesis of dithio-diphenol 4 and sulfonyl-diphenol 5, both with very bulky groups, provided starting materials for reaction sequences that led to the formation of the very stable hexacoordinated phosphorane 2 and sensitive pentacoordinated phosphorane 3. Hexacoordination was established in 2 by an intramolecular donor interaction at the phosphorus center from an oxygen atom of the sulfonyl group present as part of the eight-membered ring. The solid state structures of 2 and 3 were established by X-ray analysis, as was that of phosphite 1 formed in the reaction sequence leading to 2. In solution, 2 has two forms existing in a dynamic equilibrium between a pentacoordinated and the more dominant hexacoordinated form as determined by ³¹P and ¹⁹F NMR spectroscopy. The high stability of 2 with respect to hydrolysis and alcoholysis reactions suggests that an associative process is responsible as the controlling reaction mechanism.     

The Behavior of Phosphorus Reagents Towards Substituted Diazine and Hydrazine Derivatives

Summary. The reaction of dibenzoyldiazine with phosphorus ylides afforded the new 2-[(benzoylhydrazono)phenylalkyl]but-2-enedioic acid dialkylesters. Moreover, ethyl-2(triphenylphosphoranylidene)propionate reacts with dibenzoyldiazine to give the olefinic compound and triphenylphosphine oxide. On the other hand, oxovinylidene-triphenylphosphorane reacts with dibenzoyldiazine to give a new phosphorane adduct. Trialkyl phosphites react with dibenzoyldiazine to yield the dialkyl phosphonate products. The reaction of dibenzoylhydrazide with Wittig reagents gave rise to the new 3,7-diphenylpyrazolo[1,2-α]pyrazole-1,5-diones. Possible reaction mechanisms are considered, and the structural assignments are based on analytical and spectroscopic results.     

REACTIONS OF URACILS, 181: REACTION OF 5-FORMYL-1,3-DIMETHYL-BARBITURIC ACID AND 5-FORMYL-1,3,6- TRIMETHYLURACIL WITH ETHOXYCARBONYL- METHYLENETRIPHENYLPHOSPHORANE

Abstract

Ethoxycarbonylmethylenetriphenylphosphorane (2) reacts with 5-formyl-1,3,6-trimethyluracil (1c) in the expected way to afford the acrylate 3c, while with 5-formyl-1,3-dimethylbarbituric acid (1b) a novel phosphorus ylide/phosphorane 4 is obtained (X-ray analysis). The temperature dependent NMR spectra and the mechanism of formation are discussed.     

Synthesis of Amino Acid Derived Cyclic Phosphorus Ylides

Abstract

We recently reported the thermal elimination of Ph₃PO from suitably protected aminoacyl ylides 1 as a route to acetylenic amino acid analogues 2. Pyrolysis of ylides such as 3 with a free amino group takes a different course. Ethanol is eliminated to give the c h i d cyclic ylides 4 which can be viewed as 3-triphenylphosphoranylidene tetramic acids. Specific examples prepared include 4 (R = Me, Pri), the parent compound 5 (from glycine) and the six-membered ring compound 6 (from p-alanine). Using a similar approach, bicyclic ylides such as 7 (from proline) can be prepared. In the case of the glutamate derived ylide 8, thermolysis initially gives a mixturc of 9 and 10 but these both cyclise to the bicyclic product 11 with time. The structure and reactivity of these interesting cyclic ylides are now being examined.     

New Reactions of Halogenphosphoranes with Quinones

Abstract

It has not been known up to now that PCl₅ and p-benzoquinone can interact and form stable products. We have established that at the first stage of the reaction phosphorane (I) is formed which further undergoes different transformations depending upon the conditions.     

Preparation of (RS)-5-Amino-3-carboxypentanoic Acid (1)

(RS)-5-Amino-3-carboxypentanoic acid (1) was prepared by a Wittig reaction of N-benzoylglycinal (3) with the phosphorane (4), followed by catalytic hydrogenation and acid hydrolysis.     

FIRST EVIDENCE FOR AN YLID ⇌ PHOSPHORANE EQUILIBRIUM

Abstract

The synthesis of a salt-free ylid and of a phosphorane obtained by addition of a trivalent phosphorus compound with dimethylacetylene dicarboxylate in the presence of a trapping reagent, benzoic acid is described. This paper is concerned with the first evidence for an ylid-phosphorane equilibrium.     

A New Method of Formation of Tributyl‐β‐ keto‐ and Tributyl‐β‐alkoxycarbonylalkylidenephosphorane from Tributyl[(trimethylsilyl) methylene]phosphorane and Their Application in the Wittig Reaction

A new and efficient method of the synthesis of tributyl‐β‐keto‐ and tributyl‐β‐alkoxycarbonylalkylidenephosphorane via treatment of tributyl[(trimethylsilyl)‐ methylene]phosphorane with acid chlorides or chloroformate is described. These compounds have been studied less often than their triphenyl analogues (Maryanoff and Reitz, Chem Rev 1989, 89, 870; Taillefer and Cristau, Top Curr Chem, 2003, 229, 41; Appel, Loos, and Mayr, J Am Chem Soc 2009, 131, 704) because trialkyl‐stabilized ylides are very reactive, highly perishable, and more difficult to synthesize. This paper also presents the reaction of in situ generated tributyl‐β‐keto‐ and tributyl‐β‐alkoxycarbonylalkylidenephosphoranes with p‐nitrobenzaldehyde as a model aldehyde to obtain α,β‐unsaturated ketones and esters. All reactions result in Wittig products in a completely E‐stereoselective manner.     

Pyrolysis of Amino Acid Derived Stabilised Ylides as a Route to Chiral Acetylenic Amines and Amino Acids and Gaba Analogues

Abstract

We recently reported the pyrolysis of stabilised ylides as a method for overall conversion of carboxylic acids to homologous acetylenic esters and terminal alkynes.^1,2 This has now been applied successfully to amino acids. A wide range of alkoxycarbonyl protected amino acids have been converted to the stable crystalline ylides 1. These have been fully characterised, and upon FVP, eliminate Ph₃PO to afford the protected acetylenic amino acids 2 in good yield and without significant racemisation. Subsequent reactions of these extremely versatile intermediates have been used to gain access to a wide variety of chiral amine and amino acids of great interest as potential selective enzyme inhibitors and components for modified peptide structures.     

Anomalous Stereochemistry in the Wittig Reaction Induced by Nucleophilic Groups in the Phosphonium Ylide

Abstract

Reaction of ylides from 3–9 with benzaldehyde show that carboxylate and oxido functionalities proximate to the ylide center promote anomalously high E stereoselectivity in alkene formation. Through the use of α-deuterated ylides 12–14, an internal “trans-selective Wittig” mechanism was ruled out as a principal source of exaggerated E alkene production.     

Studies on Phosphonium Ylides XXV: The Behavior of Active Phosphacumulene and Stabilized Alkylidenephosphoranes Towards 5-(4H)-Oxazolones

The reaction of 2-phenyl-5-(4H)-oxazolone 1 and its 4-benzylidene derivative 2 with oxovinylidenetriphenylphosphorane 3 afforded 2-phenylfuro [3,2-d] [1,3]oxazol-5-(6H)-one 6 and 2,7-diphenyl-5H-pyrano[3,2-d][1,3]oxazol-5-one 7 along with triphenylphosphine. Alternatively, when 2-phenyl-5-(4H)-oxazolone 1 reacts with phosphorus ylides 4a–f the corresponding new phosphorane, the cyclic and/or the olefinic adducts were obtained. Moreover, oxazolone reacts with N-(triphenylphosphoranylidene)aniline 5 to give the new imino product 14 together with triphenylphosphine oxide. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results. Biological evaluations of the new products are also studied.     

1,3‐Dipolar Cycloadditions of Aldehydes or Imines with Carbonyl Ylides Generated from Epoxides: Classical Heating and Microwave Irradiation

Abstract

Cycloadditions of aldehydes with carbonyl ylides to give dioxolanes have been carried out without solvent under microwave irradiation. The reactions proceeded in similar yields and stereoselectivities, but in shorter reaction times, than those obtained in toluene at reflux using an oil bath. Cycloadditions conducted between imines and carbonyl ylides using the same protocol were less efficient because the oxazolidines formed proved unstable under the reaction conditions.     

Dipotassium-Hydrogen-Phosphate-Powder-Catalyzed Stereoselective C-Vinylation of Diphenylacetonitril

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by diphenylacetonitril, leads to the vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce the corresponding stabilized phosphorus ylides. Dipotassium hydrogen phosphate powder was found to catalyze the conversion of the stabilized phosphorus ylides to dialkyl(Z)-2-[cyano (diphenyl)methyl]-2-butenedioates under thermal and microwave conditions in a solventless system.     

ON THE REACTION OF BENZOTHIAZOL-2-YL SULPHENAMIDES WITH PHOSPHITES

Abstract

A study of the synthesis of phosphoramidates from phosphites and benzothiazol-2-yl-sulphenamides, indicates that a quinquecovalent phosphorane is an intermediate. Since the initial step in this reaction does not involve attack of phosphorus on nitrogen, it is unlikely that these sulphenamides will act as electrophilic aminating agents towards non-phosphorus nucleophiles. An efficient new method for preparing benzothiazol-2-yl-sulphenamides is reported.     

Ylide von Heterocyclen,III Pyridinium-Ylide von Malonylheterocyclen

Reaction of isatoic anhydride with the betaine esters2 or3 represents a new synthesis of pyridinium ylides of type5, which have been previously obtained by several other ways. Treatment of the ylide5 with inorganic acids results in the formation of their pyridinium salts5 a–d. Hydrogenation or dehydrogenation of5 with Pd/C give the piperidylquinoline9 or the betaine10, respectively. Both of them can be prepared by an alternative way. ThepK values of some pyridinium ylides were determined.

II. Mitteilung:Kappe Th., Korbuly G., Stadlbauer W., Chem. Ber.111, 3857 (1978).     

One-Pot Synthesis of Stable Phosphorus Ylides Using CH-Acid Compounds

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and di-tert-butyl acetylendicarboxylate, in the presence of antron, dimedone, indandion, and 3,5-dimethylbarbituric acid. These stable ylides exist in a solution as a mixture of two geometrical isomers 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.