Zeolite Molecular Sieve 4Å: A Reusable Catalyst for Fast and Efficient Conversion of Epoxides to Thiiranes with Thiourea

Abstract

Various epoxides are readily converted to their corresponding thiiranes by thiourea/zeolite molecular sieve 4Å system in refluxing MeOH. All reactions were carried out within 12–25 min to give thiiranes in 80%–99% yields. The catalyst saves its catalytic activity for several times at this transformation. Stereospecific conversion of (R)-(+)-styrene oxide to (S)-(+)-styrene episulfide was achieved by this combination system.

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A Convenient Synthesis of 2-Amino-1,3- selenazoles Using Ionic Liquid and Microwave Irradiation

Abstract

A simple and environmentally benign synthesis of 2-amino-1,3-selenazoles by microwave irradiation using 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄) ionic liquid (IL) is described. Acyl halides, phenacyl halides, and α-bromo-β-keto esters easily undergo condensation with selenourea in ([Bmim]BF₄) by microwave irradiation to afford the desired products of good purity in excellent yields. The ionic liquid can be easily recovered and reused at least 10 times without losing its activity. The duration of the reaction ranges from 4–6 min.

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Reactivity of Aquadiethylenetriamineplatinum(II) Ion with Disulfide Moiety Cystine: A Kinetic and Mechanistic Approach

Abstract

Substitution reactions of the complex [Pt(dien)H₂O]²⁺ (where dien = diethylentriamine or 1,5-diamino-3-azapentane) with sulfur-containing L-cystine have been studied in a 1.0 × 10^?1 mol dm^?3 aqueous perchlorate medium at various temperatures (298–323 K) and 4.45 ≤ pH ≤ 2.15 using UV-vis spectroscopy. The products obtained have been characterized by their infrared and ¹H NMR datasets at various pH levels and temperatures. From infrared and ¹H NMR data, products have indicated that [Pt(dien)H₂O]²⁺ reacted with L-cystine forming a Pt–S bond at low pH. At high pH, a product complex through the Pt–N bond has been formed. All rate constants have been evaluated from nonlinear double exponential plots. The activation parameters ΔH^# and ΔS^# have been determined using the Eyring equation. The products, S_Ni, and reversible rate constants have been evaluated.

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One-Pot Green Synthesis of 3'-(2-Aminobenzimidazolyl)-2-Phenyl Spiro[4H-Benzopyran-4,2'-Thiazolidin]-4-Ones and Acylation Using Trifluoroacetic Anhydride

Abstract

An expeditious one-pot synthesis of a novel heterocyclic system, 3′-(2-aminobenzimidazolyl)-2-phenyl spiro[4H-benzopyran-4,2′-thiazolidin]-4-ones, has been accomplished by condensing substituted hydrazinobenzimidazole, flavanone, and mercaptoacetic acid by conventional heating in ethanol or toluene, and in an ionic liquid, viz., 1-butyl-3-methyl-imidazolium hexafluorophosphate. Excellent yields (85%–90%) and higher purity are obtained in the ionic-liquid-mediated synthesis as compared with the conventional procedure (55%–60%). Further, these compounds were acylated with trifluoroacetic anhydride. The structures of the compounds were confirmed by IR, ¹H NMR, ¹³C NMR, mass spectral data, and elemental analysis. The compounds, upon evaluation for their antibacterial, antifungal, and insecticidal activities, exhibited excellent results.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Table S1, S2, and S3]

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Efficient Organic Transformations Mediated by ZrOCl2·8H2O in Water

Abstract

Operationally simple and environmentally benign methods for some organic transformations comprising reductive coupling of sulfonyl chlorides, chemoselective deoxygenation of sulfoxides, and halogenation of alcohols mediated by ZrOCl₂·8H₂O/MX in water have been developed.

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Copper (I) Iodide-Catalyzed Solvent-Free Synthesis of α-Aminophosphonates

Abstract

A method for the synthesis of α-aminophosphonates through the three-component coupling reaction of aldehydes, amines, and diisopropyl phosphite using copper (I) iodide salt catalyst is demonstrated, The reaction is highly efficient, economic, and also environment friendly.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Table S1, Figures S1–S9.]

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Si3S-, Si3Se-, Si3Te-Bicyclo[1.1.0]butanes and Si3S2-Bicyclo[1.1.1]pentane

The reaction of trisilirene 1 with propylene sulfide or elemental sulfur produced Si₃S-bicyclo[1.1.0]butane 2, which underwent Si–Si insertion of a second S atom forming Si₃S₂-bicyclo[1.1.1]pentane 3. Analogous reactions of 1 with elemental Se or Te resulted in the formation of heavier analogues of 2, namely, Si₃Se-bicyclo[1.1.0]butane 4 and Si₃Te-bicyclo[1.1.0]butane 5.

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.

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Reaction of Red Phosphorus with 4-Methoxystyrene in KOH-DMSO System: One-Pot Synthesis of Tris[2-(4-methoxyphenyl)ethyl]phosphane Oxide

Abstract

Red phosphorus reacts with 4-methoxystyrene in the KOH-DMSO superbase system (130 °C, 3 h, Ar) in the presence of a small quantity of H₂O to give tris[2-(4-methoxyphenyl)ethyl]phosphane oxide as the main product in 30% yield. Microwave activation of the reaction (600 W, 6 min) affords basically a mixture of the phosphane oxide and tris[2-(4-methoxyphenyl)ethyl]phosphane (in a ratio of 1:1). When the mixture is exposed to air (r.t., 24 h), the phosphane oxide is formed in 85% yield.

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Ab Initio Study of Conformational Properties of Heteroatom-Containing 1,2-Bisketene Analogues

Abstract

Minimum-energy and transition-state geometries of 4-oxobuta-1,3-diene-1-thione, buta-1,3-diene-1,4-dithione, 4-selenoxobuta-1,3-diene-1-thione, 4-selenoxobuta-1,3-diene-1-one, and buta-1,3-diene-1,4-diselenone were calculated using HF, B3LYP, and MP2 levels of theory and 6–31 + G* basis set by rotation around the related ?C?C? single bonds. In all of the above-mentioned molecules, the s-trans conformation was obtained as the most stable conformer with the 180° dihedral angle. In buta-1,3-diene-1,4-dithione, 4-selenoxobuta-1,3-diene-1-thione, and buta-1,3-diene-1,4-diselenone, the s-cis form of these compounds corresponded to the other energy-minimum geometry. Their skew geometries, with torsional angles approximately 100°, were a transition state for conformational interconversion between the two global minima forms. In 4-oxobuta-1,3-diene-1-thione and 4-selenoxobuta-1,3-diene-1-one, geometries with the C?C?C?C dihedral angles about 51 and 43° (respectively) were attributed to the second energy-minimum geometry. Transition-state structures from both molecules were found in the torsional angles at about 0 and 100°.

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Reaction of Nucleophilic Polyhalogenalkylation in Two and Three-Component Systems

Abstract

The halophilic reactions of the derivatives of P^III R₃ P (R = R2N, Alk, Ar) with CCl₄, having preparative signifi-cance, are studied thoroughly. As far as the compounds of R₂PHlg type are concerned, at the beginning of our re-searches there was was an opinion that the interaction of R₂PHlg with CC14 cannot be possible because of the low nucleophility of phosphorus. We determined for the first time that diamidochlorophosphites 1 react with CC14 at the temperature 20°C and form the compounds 2, 3.¹