Showing papers in "Phosphorus Sulfur and Silicon and The Related Elements in 2002"
TL;DR: An efficient synthesis of 3-substituted coumarins under solventless system is described in this article, where the synthesis of coumarin is performed using a solventless approach.
Abstract: An efficient synthesis of 3-substituted coumarins under solventless system is described.
41 citations
TL;DR: In this article, a series of dialkyl-hydroxymethylphosphonates bearing various alkyl ester groups by the Pudovik reaction is described.
Abstract: This article describes the synthesis of a series of dialkyl-hydroxymethylphosphonates bearing various alkyl ester groups by the Pudovik reaction. The employed method uses anhydrous potassium carbonate as a catalyst in heterogeneous (solid/liquid) or mixed (solid/liquid and homogenous) conditions. All these syntheses are performed without any phase transfer agent and involve an anionic intermediate in a low polar or apolar solvent. These different products, obtained with high yields, have been characterised by 1 H and 31 P NMR and also by mass spectrometry. A study of fragmentation in the FAB ionisation process is given.
41 citations
TL;DR: In this paper, a silica gel was found to catalyze conversion of dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene) butanedioates to dialkyyl 2(3-acetonaphthone)-4.
Abstract: Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by 1-hydroxy-2-acetonaphthone leads to vinyltriphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with conjugate base to produce dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene) butanedioates. Silica gel was found to catalyze conversion of dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-3-(triphenylphosphoranylidene) butanedioates to dialkyl 2-(3-acetyl-4-hydroxy-1-naphthyl)-2-butenedioates in solvent-free conditions at 90°;C in fairly good yields.
35 citations
TL;DR: In this article, the treatment of bis-(1,2-trimethylsilyloxy)-1-cyclobutene with trifluoromethylsulfenyl chloride (TMSCL) was found to furnish triflooromethodylthiolated carbonyl derivatives.
Abstract: The treatment of bis-(1,2-trimethylsilyloxy)-1-cyclobutene, 1-(1-trimethylsilyloxy)cyclpentene and 1-(1-trimethylsilyloxy)cyclohexene with trifluoromethylsulfenyl chloride has been found to furnish trifluoromethylthiolated carbonyl derivatives.
35 citations
TL;DR: In this article, the structures of the isolated products were fully determined by spectral methods, based on spectral properties of oxadiazole derivatives and triazole derivatives, respectively, and they were obtained in a good yield by the reaction of the benzylidene derivatives with acetic anhydride and yellow mercuric oxide respectively.
Abstract: Oxadiazole derivatives ( 3a , b ) and ( 4a , b ) were obtained in a good yield by the reaction of the benzylidene derivatives ( 2a , b ) with acetic anhydride and yellow mercuric oxide respectively. Cyclodesulfurization of the thiosemicarbazide derivatives ( 5a-c ) with yellow mercuric oxide afforded the oxadiazoles ( 7a-c ). On the other hand, reaction of ( 5a-c ) with sodium hydroxide gave the triazoles ( 6a-c ). The structures of the isolated products were fully determined by spectral methods.
34 citations
TL;DR: Based on 31 P NMR studies of thionyl chloride reaction with dialkyl alkylphosphonothionates, a method for preparation of alkphosphonic dichloride has been investigated as mentioned in this paper.
Abstract: Based on 31 P NMR studies of thionyl chloride reaction with dialkyl alkylphosphonothionates, a method for preparation of alkylphosphonic dichloride has been investigated. A mechanism via intermediacy of ester chloride is suggested.
31 citations
TL;DR: In this paper, the properties of synthesized compounds were established on the basis of elemental analyses, IR, 1 H NMR, and mass spectral data, and the antimicrobial activity of some synthesised compounds was reported.
Abstract: Ternary condensation of aromatic aldehydes, malononitrile and thioglycolic acid (2:2:1 molar ratio) in ethanol/piperidine afforded the corresponding thiazolo[3,2-a]pyridines 1a-d . Thiazolo[2',3':1,6]pyrido[2,3-d]pyrimidine 4 was obtained by refluxing of compound 1a with acetic anhydride. Also, thiazolopyrido pyrimidine 6 was produced by refluxing of 1a with triethylorthoformate followed by treatment with hydrazine hydrate. Refluxing 1a with formic acid yielded the thiazolopyridopyrimidine 8 which on chlorination with thionyl chloride furnished the chloro derivative 9 . Finally, amino thiazolo[2',3':1,6]pyrido[2,3-d]pyrimidine 10 was obtained by treatment of 1a with formamide. The structures of these compounds were established on the basis of elemental analyses, IR, 1 H NMR, and mass spectral data. Also, the antimicrobial activity of some synthesized compounds is reported.
29 citations
TL;DR: Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields.
Abstract: Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields.
28 citations
TL;DR: Two synthetic approaches were developed for the title compounds 8a-g via coupling of diazotized anilines with 7-acetyl-6-methyl-3-phenyl-7H-[1,2,4]triazolo[3,4-b][1,3, 4]thiadiazine as mentioned in this paper.
Abstract: Two synthetic approaches were developed for the title compounds 8a-g via coupling of diazotized anilines with 7-acetyl-6-methyl-3-phenyl-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine 7 , and reaction of N-aryl 2-oxopropanehydrazonoyl chlorides 9 with 4-amino-3-mercapto-5-phenyl-1,2,4-triazole 1 . The tautomeric structures of 8 were elucidated by their spectral analyses and correlation of their acid dissociation constants with Hammett equation.
27 citations
TL;DR: In this article, the reaction of hexamethylphosphotriamide or methylphosphonic bis(dimethylamide) compounds with amidines derived from N-Benzimidazoyl imidates leads to (1,2a)benzimidrazolo-1,3,5,2-tiazaphosphorine-2-oxides 4 in good yields.
Abstract: The reaction of hexamethylphosphotriamide or methylphosphonic bis(dimethylamide) compounds with amidines derived from N-Benzimidazoyl imidates 1 leads to (1,2a)benzimidazolo-1,3,5,2-tiazaphosphorine-2-oxides 4 in good yields. If the condensation is realized at room temperature, N-phosphonic amidines 3 can be isolated as intermediates. The isolated compounds 2 , 3 , and 4 are identified by spectroscopic methods: IR, 1 H, 13 C, 31 P, NMR, and M.S.
26 citations
TL;DR: In this article, the conformations around P and Se in 8-(PhSe)-1-(Ph 2 P=O)C 10 H 6 are determined by the attractive O·;·; · ·;··;Se--C 3c-4e type interaction.
Abstract: The lone pair-lone pair repulsion plays an important role in the nonbonded P·;·;·;P interaction in naphthalene 1,8-positions. The conformations around P and Se in 8-(PhSe)-1-(Ph 2 P=O)C 10 H 6 are determined by the attractive O·;·;·;Se--C 3c-4e type interaction. The P·;·;·;Se interaction in the 1,8-positions is also discussed.
TL;DR: In this paper, the NH-acids such as pyrrole, indole, imidazole, or benzimidazoles were added to methyl or ethyl propiolate under neutral conditions in the presence of a catalytic amount of triphenylphosphine.
Abstract: The f -addition of NH-acids such as pyrrole, indole, imidazole, or benzimidazole to methyl or ethyl propiolate proceeds under neutral conditions in the presence of a catalytic amount of triphenylphosphine to give the corresponding f -substituted alkyl acrylates.
TL;DR: In this paper, the 1 H NMR spectra of stabilized ylides obtained from 2-acetylpyrrole and indole were analyzed and attributed to restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.
Abstract: Crystalline phosphorus ylides are obtained in excellent yields from the addition reaction between triphenylphosphine, dimethyl acetylenedicarboxylate and strong NH-acids, such as 2-acetylpyrrole, indole, ethyl 3-indolylglyoxalate and N -benzyl-2-pyrrolylglyoxamate. Dynamic NMR effects are observed in the 1 H NMR spectra of stabilized ylides obtained from 2-acetylpyrrole and indole ( j G p = 67.1 and 68.8 kJmol m 1 respectively) and are attributed to restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.
TL;DR: In this article, the authors performed the Willgerodt-Kindler reaction to obtain thiobenzmorpholide under both classical (reflux, room temperature) and nonclassical (microwave) conditions to attempt their elucidation of the reactions pathways.
Abstract: On the benzyl system, bearing various functional groups, have been carried out the Willgerodt-Kindler reaction to obtain thiobenzmorpholide ( 1 ). The reactions, under solvent-free conditions, were performed in both classical (reflux, room temperature) and nonclassical (microwave) conditions to attempt our elucidation of the reactions pathways. Unlike benzylamine and benzyl mercaptan, benzyl halides give poor result due to the type of amine. The experimental results suggest that the proposed reaction pathway involves the oxidation coupling of benzylic substrates, followed by a thiolation step and an attack of the amine on the thiolated product to give ( 1 ).
TL;DR: Some 2,3-dihydro-1,3,4-thiadiazoles containing pyrazol-3-yl, indolin-2-one-2yl and indan-1.3d-dione-2.2-yl moieties were obtained from the reaction of hydrazonoyl halides with thiocarbamate and carbodithioate in ethanolic triethylamine as discussed by the authors.
Abstract: Some new 2,3-dihydro-1,3,4-thiadiazoles containing pyrazol-3-yl, indolin-2-one-2-yl and indan-1,3-dione-2-yl moieties in a good yields obtained from the reaction of hydrazonoyl halides with thiocarbamate and carbodithioate in ethanolic triethylamine respectively. In contrast, pyrazolylthiourea reacts with hydrazonoyl halides under the same condition afford corresponding hydrazonoyl sulfide derivatives.
TL;DR: In this article, a 2-picolylselenolate/tellurolate was obtained by reacting lithiated 2picoline with elemental selenium/tellurium, which upon aerial oxidation gave 2,2'-dipicolyl diselenide in case of seenium while 1,2-bis(2-pyridyl)ethane in the case of tellurium.
Abstract: Lithium 2-picolylselenolate/tellurolate is obtained by reacting lithiated 2-picoline with elemental selenium/tellurium which upon aerial oxidation gives 2,2'-dipicolyl diselenide in case of selenium while 1,2-bis(2-pyridyl)ethane in case of tellurium. Condensation of 2-picolylselenolate anion with a variety of electrophiles provides a facile synthesis of 2-picolylalkyl selenides in good to excellent yields. Quenching of lithiated 2-picoline with 2,2'-dipyridyl diselenide gives mixed 2-picolylseleno pyridine in low yield. All the compounds prepared are new and have been characterized by elemental analysis, 1 H NMR, 13 C NMR and mass spectral studies.
TL;DR: In this paper, two synthetic methods leading to the new n, n '-diphosphonylketones 2 and 2'are reported, one involves the base-catalyzed addition of diethylphosphite to diarylideneketones.
Abstract: Two synthetic methods leading to the new n , n '-diphosphonylketones 2 and 2 ' are reported. The first method involves the base-catalyzed addition of diethylphosphite to diarylideneketones. The second one utilizes the reaction of triethylphosphite and ethoxydiphenylphosphine with g , g '-bis(dimethylamino)ketone hydrochlorides. On reaction with phenylhydrazine hydrochloride, compounds 2 and 2 ' give the corresponding 2-(phosphonoethyl)3-(phosphonomethyl)indoles 3 . The structure of all obtained products is confirmed by NMR ( 1 H, 31 P, 13 C) and IR spectroscopy.
TL;DR: 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 as mentioned in this paper.
Abstract: Stable crystalline phosphorus ylides are 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 hydantoin and 5,5-dialkylhydantoins. These stable ylides exist in 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.
TL;DR: In this paper, a general method for the synthesis of polyphosphonic acids is described, which is then hydrolyzed with HCl to give the corresponding polyphonic acids.
Abstract: A general method for the synthesis of new polyphosphonic acids is described. The hexaisopropyl alkane-1,1,n-triphosphonates (n = 4-5) are formed by the reaction of the salt of tetraisopropyl methylenediphosphonate with diisopropyl n-bromoalkanephosphonates (n = 3-4) while the hexaisopropyl alkane-2,2,n-triphosphonates (n = 5-6) are formed by the reaction of the salt of tetraisopropyl ethane-1,1-diphosphonate with diisopropyl n-bromoalkanephosphonates (n = 3-4). The esters are then hydrolyzed with HCl to give the corresponding phosphonic acids.
TL;DR: Dimethyl thiophosphite reacts with aliphatic aldehydes and ketones, Michael acceptors, and N-benzyl imines to afford excellent yields of f -hydroxy phosphonothionates, g -substituted phosphon-ionates and f -amino phosphonithionates as discussed by the authors.
Abstract: Dimethyl thiophosphite reacts with aliphatic aldehydes and ketones, Michael acceptors, and N-benzyl imines to afford excellent yields of f -hydroxy phosphonothionates, g -substituted phosphonothionates and f -amino phosphonothionates, respectively. Dealkylation of f -amino phosphonothionates affords N-benzyl f -amino phosphonothioic acids. Dimethyl thiophosphite reacts with electrophiles at a significantly greater rate than dimethyl phosphite.
TL;DR: 4H-Imidazolin-4-ones 3 and 4 were synthesized respectively by base catalytic reactions of 4-methylthiophenol or phenthiol with carbodiimides with aromatic isocyanates and exhibited good fungicidal activity against Pellicularia sasakii.
Abstract: 4H-Imidazolin-4-ones 3 and 4 were synthesized respectively by base catalytic reactions of 4-methylthiophenol or phenthiol with carbodiimides 2 , which were obtained via aza-Wittig reaction of iminophosphorane 1 with aromatic isocyanates. 3 and 4 exhibited good fungicidal activity against Pellicularia sasakii.
TL;DR: In this article, a method for the preparation of various methyl substituted 2,2'-dipyridyl diselenides and -ditellurides by the aerial oxidation of lithium 2-pyrideselenolate/tellurolate, prepared from the lithium-halogen exchange between n-butyllithium and 2-bromo methyl substituted pyridines is reported.
Abstract: A convenient method for the preparation of various methyl substituted 2,2'-dipyridyl diselenides and -ditellurides by the aerial oxidation of lithium 2-pyridylselenolate/tellurolate, prepared from the lithium-halogen exchange between n-butyllithium and 2-bromo methyl substituted pyridines is reported. All the compounds prepared are new and have been characterized by elemental analysis, IR, 1 H, 13 C, 11 Se NMR, and mass spectral studies. Crystal structure of 6,6'-dimethyl-2,2'-dipyridyl diselenide has been determined.
TL;DR: It is found that the above phenomena all undergo penta-coordinate intermediate of phosphorus atom, which is proposed as the key factor to determine their activities.
Abstract: The relationship between penta-coordinate phosphorus compounds and biochemistry is briefly reviewed. Some interesting phenomena such as peptide formation, ester formation, ester exchange on phosphorus and N to O migration occur at room temperature when the amino group of amino acid is associated with phosphoryl group. Serine or threonine in conjugate of nucleo-side-amino acid could recognize different nucleobases. N-phosphoryl Histine and Ser-His dipeptide could cleavage nucleic acid, protein and ester in neutral medium. It is found that the above phenomena all undergo penta-coordinate intermediate of phosphorus atom, which is proposed as the key factor to determine their activities.
TL;DR: In this paper, a ring expansion of triazolobenzothiadiazocin-11-one was used to synthesize an aryl isocyanate.
Abstract: Several [1,2,4]triazolobenzothiadiazocin-11-ones 3 were prepared via ring expansion of [1,2,4]triazolo[3,2-b][2,4]benzothiazepin-10(5H)-ones 1 in presence of sodium azide. The reaction intermediate was isolated and characterized as an aryl isocyanate 2b . A possible pathway for formation of novel triazolobenzothiadiazocin-11-one 3 is described.
TL;DR: Several 3-substituted-(un)-cyclohepta(b)thieno[2,3-d]pyrimido[3,4a]-1,2,4-triazoles 10, 11, 12, 13, and 14 were prepared by reaction of an appropriate substituted 2-amino-3-cyanothiophene 1 with aliphatic acids or benzoyl chloride as mentioned in this paper.
Abstract: Several 3-substituted-(un)-cyclohepta(b)thieno[2,3-d]pyrimido[3,4-a]-1,2,4-triazoles 10 , 11 , 12 , 13 , and 14 were prepared by reaction of an appropriate substituted 2-amino-3-cyanothiophene 1 with aliphatic acids or benzoyl chloride. Also the fusion of 1 with urea, thiourea to give the corresponding 2-oxo or thioxo-4-aminopyrimidine derivatives 6a , b and other reactions of compound 1 are reported.
TL;DR: In this paper, the synthesis of some phosphonate esters under solvent free condition was described, which are easy, rapid, and high-yielding reactions for synthesizing the esters.
Abstract: Phosphonate esters are versatile intermediate in organic synthesis. These compounds have found a wide range of application in the areas of industrial, agricultural, and medicinal chemistry owing to their physical properties as well as their utility as synthesis intermediates. The synthesis of some phosphonate esters under solvent free condition was described. These methods are easy, rapid, and high-yielding reactions for the synthesis of phosphonate esters.
TL;DR: In this paper, a simple and fast synthesis of 6-aryl-3-substituted-5H-[1,2,4]-triazolo[4,3-b][1, 2,4]triazoles 4 in high yields has been developed by microwave assisted heterocyclization.
Abstract: A simple and fast synthesis of 6-aryl-3-substituted-5H-[1,2,4]-triazolo[4,3-b][1,2,4]triazoles 4 in high yields has been developed by microwave assisted heterocyclization of N-(3-methylthio-5-substituted-4H-1,2,4-triazol-4-yl)benzenecarboximidamides 3 . The effectiveness of the microwave irradiation and conventional heating for the formation of compounds 4 has been investigated.
TL;DR: In order to search for new chelating agents, widely employed methodologies in the chemistry of organophosphorus compounds such as the Michaelis-Arbuzov and Michaelis Becker reactions were used to synthesize new bisphosphonates in high yields.
Abstract: In order to search for new chelating agents, widely employed methodologies in the chemistry of organophosphorus compounds such as the Michaelis-Arbuzov and Michaelis-Becker reactions were used to synthesize new bisphosphonates in high yields. The importance of the synthesis of these compounds resides in their potential capability of complexing different metals, all the more so because bisphosphonates have been widely employed in the diagnosis and therapy of several bone diseases, such as osteoporosis and hypercalcemia, as extracting agents for alkaline, alkaline earth, and transition metals, and also as reaction catalysts. All bisphosphonates synthesized were characterized by IR, 1 H-NMR, 13 C-NMR, 31 P-NMR, and mass spectroscopy.
TL;DR: In this paper, a smooth reaction with dialkyl 2-(1,1-dioxo-1 H -1 u 6 -benzo[ d ]-isothiazol-3-yl)-but-2-enedioates in boiling toluene is described.
Abstract: Saccharin (1,1-dioxo-1,2-dihydro-1 u 6 -benzo[ d ]-isothiazol-3-one) undergoes a smooth reaction with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine to produce highly-functionalized salt-free sulfur-containing ylides in nearly quantitative yields. These stabilized phosphorus ylides exist 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. These ylides are converted to dialkyl 2-(1,1-dioxo-1 H -1 u 6 -benzo[ d ]-isothiazol-3-yl)-but-2-enedioates in boiling toluene.
TL;DR: Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and strong NH-acids.
Abstract: Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and strong NH-acids, such as acetanilide, 4-methylacetanilide, 2-cyanoacetanilide, 4-bromoacetanilide, 4-methoxyacetanilide, succinimide, malimide, or phthalimide. These stabilized phosphoranes exist 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.