Reflux In Benzene Research Articles

The Study of the Kinetics of Intramolecular Radical Cyclizations of Acylsilanes via the Intramolecular Competition Method

The kinetics of the radical cyclizations of acylsilanes is probed by the construction of an intramolecular competition system. In this system, known rate constants of olefin cyclizations are used as the internal clock. At benzene reflux temperature (80 °C), the cyclization rate constants for 5-exo cyclizations of acylsilanes with primary radicals are on the order of 106 s-1. The corresponding rate constants for 5-exo cyclizations with secondary radicals and 6-exo cyclizations with primary radicals lie on the order of 105 s-1. The 6-exo cyclizations of acylsilanes with secondary radicals are slower and fall in the range of 104 s-1. Substituents on the silicon of the acylsilanes affect the rates of cyclization. Large silyl groups reduce the rate, and this is more serious for the 6-exo type of cyclizations. Electron-withdrawing groups increase the rates of cyclization.

Thermal rearrangements of C-(4-Oxo-4 H[1]benzopyran-3-yl)- N-phenylnitrone-a route to novel quinolino[2,3- b]chroman-12-ones

C-(4-Oxo-4 H[1]benzopyran-3-yl)- N-phenylnitrones ( 1a-c) undergo facile rearrangements on refluxing in benzene, yielding 2-( N-phenylamino)-4-oxo-4 H[1]-benzopyran-3-carboxaldehydes ( 2a-c, 70%) and 3-(phenyliminomethylene)-chroman-2,4-diones ( 3a-c, 25%). 2a-c undergo cyclization on refluxing with anhydrous AlCl 3 in dry CCl 4 followed by treatment with sulfuric acid, to give novel quinolino[2,3- b]chroman-12-ones( 4a-c) in 90% yield.

Photochemical [3+2] Cycloaddition of 2'-Vinyl-2H-1,4-benzothiazin-3(4H)-one-2-spirocyclopropanes Catalyzed by Diphenyl Dichalcogenides.

2'-Vinyl-2H-1, 4-benzothiazin-3(4H)-one-2-spirocyclopropanes (1) were irradiated with a tungsten lamp at room temperature in the presence of a catalytic amount of diphenyl dichalcogenide to provide 1, 2-dioxolane derivatives (3) in good yields. Diphenyl diselenide was more effective than diphenyl disulfide as a radical source. The photochemical [3+2] cycloaddition of 1b with electron-deficient alkenes proceeded smoothly under reflux in benzene to give spiro-cyclopentanes (5). Spiro-cyclopentenes (6) were formed by the photochemical [3+2] cycloaddition of 1b with alkynes.

Parallel vs. perpendicular alkyne coordination in binuclear complexes. The first examples of reactivity differences in isomers differing in their alkyne coordination modes

The reaction of [Ir2(CO)3(dppm)2] (dppm = Ph2PCH2PPh2) with dimethyl acetylenedicarboxylate (DMAD) first yields [Ir2(CO)2(μ-η1:η1-DMAD)(dppm)2] (2) in which the alkyne is bound parallel to the metal–metal axis and the diphosphines are bound in a trans arrangement at both metals. This metastable isomer slowly rearranges to the stable form, [Ir2(CO)2(μ-η2:η2-DMAD)(dppm)2] (3), in which the alkyne is now bound perpendicular to the metals and the diphosphines are bent back in a cis arrangement at both metals. The analogous species can be prepared by substituting hexafluoro-2-butyne (HFB) for DMAD; however, for the HFB adduct the isomer having the parallel geometry is seen only as a transient species; only [Ir2(CO)2(μ-η2:η2-HFB)(dppm)2] (5) was isolated. Compound 2 reacts readily with PMe3 to yield [Ir2(CO)(PMe3)(μ,-CO)(μ-η1:η1-DMAD)(dppm)2], and with CH3OSO2CF3 to yield [Ir2(CH3)(CO)2(μ-η1:η1-DMAD)(dppm)2][SO3CF3], whereas 3 reacts with neither reagent. Both 2 and 3 react with HBF4•OEt2 to yield the respective alkyne-bridged hydrides, [Ir2H(CO)2(μ-η1:η1-DMAD)(dppm)2][BF4] and [Ir2H(CO)2(μ-η2:η2-DMAD)(dppm)2][BF4], in which the gross structural features and the alkyne coordination mode of the precursor are retained in each case. The latter species rearranges readily at ambient temperature, via migratory insertion, to give the vinyl-bridged product, [Ir2(CO)2(μ-η1:η2-RC=C(H)R)(dppm)2][BF4] (R = CO2Me); however, the former is inert under these conditions, yielding the above vinyl species together with other decomposition products only upon reflux in benzene for several hours. Protonation of the perpendicular hexafluoro-2-butyne adduct also yields the corresponding vinyl product, together with decomposition products. The structure of 3, as the methylene chloride disolvate, was established by X-ray analysis. Crystal data are as follows. 3•2CH2Cl2: C60H54Cl4O6P4Ir2, monoclinic, P2/c, a = 26.088(5) Å, b = 9.896(4) Å, c = 23.954(3) Å, β = 109.27(1)°, Z = 4, R(F) = 0.038, Rw(F2) = 0.0997 (all data). Key words: diiridium alkyne complexes, parallel and perpendicular alkyne coordination.

An Investigation of the Reactivity of [Rh2Cp∗2(μ-CO)2] (Cp∗ = η5-C5Me5) Towards Triorganosilanes: Isolation and Characterization of [RhCp∗(CO)(H)(SiPh3)] and Some Related Compounds

Abstract The reactions of the unsaturated Rh=Rh complex [Rh2Cp∗ 2(μ-CO)2] with triorganosilanes (Ph3SiH, Et3SiH, Me2PhSiH) have been investigated. With Ph3SiH at benzene reflux, the unstable rhodium(III) species [RhCp∗(CO)(H)(SiPh3)] is formed in high yield by symmetric cleavage of the rhodium dimer. With Et3SiH and Me2PhSiH at toluene reflux, the stable rhodium(V) species [RhCp∗(H)2(SiR3)2] are formed in addition to the unstable rhodium(III) [RhCp∗(CO)(H)(SiR3)] complexes; longer reaction times favour formation of the rhodium(V) products. These triorganosilyl hydride complexes have been characterized by IR and NMR (1H, 29Si) spectroscopy.

Synthesis and Structural Study of New Saturated Isoindol-1-one Derivatives

Condensation of 2-p-toluoy1cyclohexanecarboxylic acid (la,b) with primary amines gave the corresponding hexahydroisoindol-I-ones (2a-g) in good yield. The octahydro derivatives (4a-g) were prepared from cis- and trans-hexahydro- 1 (2H)-phthalazinone (3a,b)hy reductionwith zinc-hydrochloricacid viaring contrac- tion. Stereoselective synthesis of cis-N-phenyloctahydroisoindol-I-one (4h) was performed starting from 2b by reduction with magnesium-methanol at room temperature. Configurational assignments of cis and trans isomers were based on 'H- and L3C-nmr spectroscopic studies. The 3-arylisoindol-1-one derivatives have been associated with important pharmacological properties, such as antiarrhytmic, antitussive, and antiinflammatory activities among Synthesis of these compounds was carried out mostly from corresponding 1.4-dicarbonyl compounds by reductive cyclisation with primary amine~.~.~ Yamamoto eta/. prepared N-phenyl substituted isoindolines from aromatic isocyanates7 In the course of our work we investigated the reactions ofthe cyclohexane condensed keto acids with primary amines, with the aim to synthesize pharmacologically active derivatives. The conditions of these reactions were strongly determined by the basicity of applied amines. Alkyl- or cycloalkylamines (e.g cyclohexylamine) reacted readily under relatively mild conditions (reflux in benzene or toluene for several hours) with keto acid (la,b) but

Efficient Synthesis of Long-Chain Furanoid Fatty Ester Derivative From Methyl Ricinoleate

Abstract The reaction of methyl (Z)-9,10-epoxy-12-oxoocta-decanoate (2) with ammonium azide, generated in situ from sodium azide and ammonium chloride in aqueous ethanol affords methyl 8-(5-hexylfuran-2-yl)octanoate (1b) in 98% yield. Compound 1b was also prepared in >90% yield by reacting compound 2 with the following Lewis acids: aluminium(III) chloride, tin(IV) chloride, zinc(II) chloride under reflux in benzene or dichloromethane; or at ambient temperature with tin(II) bromide or hydrated tin(II) chloride in dichloroethane.

Dichloromethyl tert-butyl ketone in the Darzens reaction

The condensation of dichloromethyl tert-butyl ketone (1) with benzaldehyde, para-bromobenzaldehyde, and 2,4-dichlorobenzaldehyde under conditions for the Darzens reaction gives 1-aryl-1-chloro-4,4-dimethyl-2,3-pentanediones (2–4). In the case of nitrobenzaldehydes, the reaction products are 1-aryl-2-chloro-1,2-epoxy-4,4-dimethylpentanones (5 and 6), which isomerize to α-chloroketones (7 and 8) upon prolonged storage or heating at reflux in benzene.

Cobalt mediated cyclisations of epoxy olefins

Irradiation of solutions of β-hydroxycobaloximes e.g. (2), (5), (9) and (13) derived from epoxy olefins [ e.g. (1), (8) and (12)] and cobalt(I) dimethylglyoxime, using a sunlamp at room temperature, leads to facile cyclisation producing cycloalkanols e.g. (4), (6), (10) and (14). By contrast, only the products viz (3), (7) and (11) of dehydrocobaltation are produced when the same β-hydroxycobaloximes are heated under reflux in benzene.

Stannadesulfurization of a bis(diethyldithiocarbamato)tungsten(II) complex. Formation of an aminocarbynetungsten complex

The crystalline, blue, diamagnetic complex [(W(η 2 -S 2 CNEt 2 )) 2 (μ-CNEt 2 )(μ-S)(μ-S 2 CNEt 2 )(μ-S 2 SnR 2 )]-(W,W) (3) was obtained by heating [W(CO) 2 (η 2 -S 2 CNEt 2 ) 2 (SnR 2 )] (R=CH(SiMe 3 ) 2 ) under reflux in benzene: single-crystal X-ray data on 3 confirm its structure

ChemInform Abstract: 1‐Phenylthio‐1‐(trimethylsiloxy)cyclopropanes via the Sila‐Pummerer Rearrangement.

AbstractThe 1‐silylcyclopropyl phenyl sulfides (I) are converted to the sulfoxides (IIa) ‐ (IIc) which rearrange upon refluxing in benzene, forming the 1‐siloxycyclopropyl sulfides (III).

Reactions of Per-O-Acetylated Carbohydrate Triflates With Halide Ions

Abstract The reactions of bromide, chloride, and iodide ions with 1,3,4, 6-tetra-O-acetyl-2-O-(trifluoromethylsulfonyl) -α-D-glucopyranose (2) and with 1, 3, 4, 6-tetra-O-acetyl-2-O-(trifluoromethylsulfonyl)-β-D-mannopyranose (3) gave good to excellent yields of the corresponding deoxyhalogeno sugars. In contrast, when the gluco triflate 2 and tetra-butylammonium fluoride were heated under reflux in benzene, only 5-(acetoxymethyl)-2-formylfuran (13) was formed. Reaction of the manno triflate 3 under similar conditions produced 1, 3,4, 6-tetra-O-acetyl-2-deoxy-2-fluoro-β-D-gluco-pyranose (17), 1. 3, 4. 6-tetra-O-acetyl-2-deoxy-β-D-erythro-hex-2-eno-pyranose (18), 4,6-di-O-acetyl-1, 5-anhydro-2-deoxy-D-erythro-hex-l-enitol-3-ulose (19), and 1, 2, 3, 4, 6-penta-O-acetyl-β-D-glucopyranose (20). The mechanisms of the reactions of The triflates 2 and 3 with fluoride ion are discussed.

Ｓｙｎｔｈｅｓｉｓ ｏｆ Ｎｏｖｅｌ Ｃａｒｂｏ‐ ａｎｄ Ｈｅｔｅｒｏｐｏｌｙｃｙｃｌｅｓ ＶＩ アダマンタン関連橋頭位および橋かけ位アジドと三価リン化合物との反応

The reactions of 1-adamantyl azide [1 a], 2-adamantyl azide [1 b], , 2-methyl-2-adamantyl azide [1 c], , 3-homoadamantyl azide [1 d], , and bicyclo[3.3.1]non-1-y1 azide [1 e], with P(C6H5)3 [2 a], , P(n-Bu)3 [2 b], 1 and P(OEt)3 [2 c], were examined in order to prep are the corresponding iminophosphoranes. The relative reactivity of [1 a], in the reactions of [2a]-[2c], under reflux in benzene for 1 h was shown to be 1.0 0: 16.5: 8.50 based on the IR spectra. The relative reactivity of [2 a], in the reactions of [1 a]∼[1 e], under the same conditions as above was shown also as 1.00: 10.2: 0.58: 1.76. The corresponding iminophosphoranes [5 a], , [5 b], , and [5 c], from [1 a], with [2 b], and [2 c], , and from [1 b], with [2 a]respectively were obtained in high yields. Some examples of their applications on synthesis of adamantyl isocyanate, isothiocyanate, and carbodiimide, and/or their derivatives were also reported.

化粧品中の天然ワックスの分析法について

Systematic detection and determination of natural waxes, paraffin, microcrystalline wax, ceresin, bees wax (high acid value), candelilla wax, carnauba wax, lanolin, spermaceti and Japan wax in cosmetics have been established as follows.The natural waxes which were extracted from cosmetics under benzene reflux, were separated into five fractions by Florisil column chromatography; n-hexane fraction (hydrocarbons), 20% diethyl ether in n-hexane fraction (esters of higher alcohol and fatty acid), 60% diethyl ether in n-hexane fraction (triglycerides and free alcohols), 5% dichloromethane in diethyl ether fraction (mono- and diglycerides) and 5% acetic acid in diethyl ether fraction (free fatty acids). The components of each fraction were identified by thin layer chromatography and gas chromatography. The specific peaks of gas chromatograms of sample were compared with those of standard natural waxes, and then natural waxes contained in cosmetics were determined.This procedure is useful for rapid and simple components analysis of natural waxes as quality control of starting materials for cosmetics.The analyses of natural waxes in lip stick, hair stick and cream were obtained more than 75% for prepared content.

Reactions of pyrazolo(1,5-a)pyrimidine derivatives with nucleophiles. IV. Some reactions of 1,4-dihydrocyclopent(b)indoles.

4, 7-Dihydro-4-methyl-7-(N-methyl-3-indolyl) pyrazolo [1, 5-α] pyrimidine (3) obtained from pyrazolo [1, 5-α] pyrimidine (1) was treated with indole in the presence of an excess of triethyloxonium fluoroborate to give a mixture of 1, 4-dihydro-3-(3-indolyl) cyclopent [b] indoles (5, 6, 7 and 8). The reaction of 6 with potassium hydroxide in ethanol at room temperature gave the 1-hydroxy derivative (10), while under reflux 6 gave 1, 4-dihydro-1-oxocyclopent [b] indole (11). Treatment of 6 with formaldehyde gave the 1-hydroxymethyl derivative (13). m-Chloroperbenzoic acid oxidation of 6 afforded the 3, 4-dihydrocyclopent [b] indole (14). Furthermore, the reaction of 6 with activated olefins, such as maleic anhydride, maleimide, acrylonitrile and ethyl acrylate under reflux in benzene or acetonitrile gave [4+2] cycloadducts, bicyclo [2.2.1] hept [2, 3-b] indoles (17, 18, 20 and 21), via the 2, 4-dihydrocyclopent [b] indole intermediate (6').

ChemInform Abstract: STUDIES ON HETEROCYCLIC COMPOUNDS. XXXIV. SYNTHESIS OF 2‐SUBSTITUTED AMINOBENZOXAZOLES WITH NICKEL PEROXIDE

AbstractDie durch Addition des Aminopicolins (I) an die Senf Öle (II) zugänglichen Thioharnstoffe (III) lassen sich mit Ni‐peroxid zu den Harn‐ Stoffen (IV) entschwefeln; diese sind auch aus (I) und den Isocyanaten (V) erhältlich.

Studies on heterocyclic compounds. XXXIV. Synthesis of 2-substituted aminobenzoxazoles with nickel peroxide.

Oxidation of N-methyl (or phenyl)-N'-(4-methylpyrid-2-yl) thiourea (Ia, b) with nickel peroxide (Ni-PO) under reflux in benzene or acetonitrile afforded the corresponding ureas (IIa, b). N-(2-Hydroxy-5-methylphenyl)-N'-methylthiourea (IVa) was synthesized by the reaction of 2-amino-4-methylphenol (III) and methyl isothiocyanate in benzene under reflux. However, the reaction of III and phenyl isothiocyanate in benzene under reflux did not afford the thiourea (IVb) but IVb was obtained in ethanol at room temperature. Ni-PO oxidation of thioureas (IVa-f) in acetonitrile at room temperature afforded 2-substituted aminobenzoxazoles (VIIa-f) in good yields. The reaction mechanisms of Ni-PO and thioureas (Ia, b and IVa-f) are discussed.

Synchronous skeletal rearrangement ofD- nor-5α-androstane-16α- and -16β-carbonyl m-chlorobenzoyl peroxides

The reaction of D-nor-5α-androstan-16β-carbonyl chloride, a steroidal cyclobutanecarbonyl chloride, with m-chloroperbenzoic acid leads via rearrangement to a C-homo-D-bisnor-steroid. In contrast, the 16α-isomer with m-chloroperbenzoic acid afforded the corresponding stable acyl aroyl peroxide which underwent competitively a carboxy-inversion reaction and the migration of the 13β-methyl group upon reflux in benzene.

Reactions of zero-valent platinum–sulphur dioxide complexes with dienes; isolation and X-ray crystal structure of a novel, µ-phenyl, µ-phosphido-, µ-sulphur dioxide triangulo-triplatinum cluster

The complex Pt(SO2)2(PPh3)2 reacts with butadiene and isoprene to give the complexes Pt(1,2-η-C4H5R)(SO2)(PPh3)2(R = H or Me) which, on refluxing in benzene, afford high yields of the triangulo-cluster compound Pt3(µ-Ph)(µ-PPh2)(µ-SO2)(PPh3)3, characterised by a single crystal X-ray diffraction study.

Preparation of secopenicillanates; preparation of methyl 3-methyl-2-[(2R,3R)-2-methylthio-4-oxo-3-phthalimidoazetidin-1-yl]but-2-enoate

Treatment of methyl (1R,6R)-1-oxo-6-phthalimidopenicillanate (4) with trimethyl phosphite gives a mixture of bis-{(2R,3R)-1-[(1R)-1-methoxycarbonyl-2-methylprop-2-enyl]-4-oxo-3-phthalimidoazetidin-2-yl} disulphide (12)(25–60%) and methyl (2R)-3-methyl-2-[(2R,3R)-2-methylthio-4-oxo-3-phthalimidoazetidin-l-yl]but-3-enoate (11)(15-35%). The latter compound was also prepared by heating methyl (1R,6R)-1-oxo-6-phthalimidopenicillanate sulphoxide in 2-methylpropane-1-thiol, under reflux, to give the unsymmetrical disulphide (21) which was cleaved by trimethyl phosphite to give the non-conjugated secopenicillanate (11). Conversion of the non-conjugated secopenicillanate (11) into methyl 3-methyl-2-[(2R,3R)-2-methylthio-4-oxo-3-phthalimido azetidin-1-yl]but-2-enoate (2) was achieved using a catalytic amount of diazabicyclononene (DBN) at room temperature. Prolonged treatment with DBN under reflux in benzene, gave a mixture of the conjugated secopenicillanate (2) and its 3′-epimer (22) in a ratio of 3 : 7.