Manganese(III)-based oxidation of 1,2-disubstituted pyrazolidine-3,5-diones in the presence of alkenes

The manganese(III)-catalyzed aerobic oxidation of 1,2-disubstituted pyrazolidine-3,5-diones 1 in the presence of alkenes 2 gave the corresponding pyrazolidinediones 3 which were doubly hydroperoxyalkylated at the 4-position in high yields. On the other hand, pyrazolidinediones 1 were oxidized with manganese(III) acetate in the presence of alkenes 2 at elevated temperature to produce the 4,4-bis(alkenyl)pyrazolidinediones 4 in good yields instead of the pyrazolidine-fused dihydrofuran analogue IV. A similar cerium(IV)-mediated oxidation of pyrazolidinedione 1a with an alkene 2a afforded the doubly 4-methoxyethylated derivative 5. The stability of the free hydroperoxyl group and the reaction pathway for the aerobic and the metal-mediated oxidation reactions were also discussed.     

3,5-二(吡啶-甲氧基)苯甲酸吡啶-甲基酯的合成

具有三脚架构型的多吡啶类化合物,因其具有众多的配位原子以及较为特殊的分子构型,在与金属离子配位的过程中,一方面可以通过吡啶氮的配位键、氢键、芳香环的π-π作用等方式构筑出结构新颖的配合物[1-4];另一方面因其具有三脚架的构型,其三条侧链可自由翻转形成大小合适的空腔,能够与不同的客体分子或离子结合,有可能筛选出在分子识别、分子交换、电子传递和选择性催化等方面具有特殊性能的功能材料[5-8].因此,合成具有三脚架构型的多吡啶类配体是这些配合物在诸多领域中应用的关键.     

Reaction of acetone oxime with dialkylmalonyl chlorides. Synthesis of 2-(2-propenyl)isoxazolidine-3,5-diones and 2,2-bis-(2-(4,4-dialkylisoxazolidine-3,5-dione))propanes

Reaction of acetone oxime with dialkylmalonyl chlorides in the presence of triethylamine gave as products 2-(2-propenyl)-4,4-dialkylisoxazolidine-3,5-diones 4 and 2,2-bis-(2-(4,4-dialkylisoxazolidine-3,5-dione))propanes 5 . The 4,4-dialkylisoxazolidine-3,5-diones 6 and dimethylketoximyl 4,4-dialkylmalonates 7 were formed as minor products. Compounds 4 are stable in refluxing ethanol and in aqueous solution. Compounds 5 are stable when heated in refluxing toluene in the presence of either pyridine or monochloroacetic acid.     

One-pot Synthesis of 3-Aryl-1,5-bis（2-hydroxyaryl）pentane-1,5-diones

A simple method for the synthesis of 3-aryl-1,5-bis(2-hydroxyaryl)pentane-1,5-diones is developed by one-potreaction involving 2-hydroxyacetophenone and arylaldehyde in aqueous potassium hydroxide.     

Kinetics of iron(III)-catalyzed autoxidation of sulfur(IV) in acetate buffered medium

The kinetics of the environmentally important oxidation of sulfur(IV) by oxygen in acetate buffered medium in the presence of Fe(III) and the pH range 5.27–5.70 has been studied. The results were in agreement with the rate law:

Synthesis and characterization of phase-pure manganese(II) and manganese(III) silicalite-2

Manganese silicalite-2 was synthesized at high pH using the molecular cluster Mn 12O 12(O 2CCH 3) 16 as a Mn source. The silicalite-2 (ZSM-11) materials were synthesized using 3,5-dimethyl- N, N-diethylpiperdinium hydroxide as a structure-directing agent to produce phase-pure ZSM-11 materials. No precipitation of manganese hydroxide was observed, and synthesis resulted in the incorporation of up to 2.5 mol % Mn into the silicalite-2 with direct substitution into the framework verified by the linear relationship between the unit cell volume and loading. The Mn is reduced to Mn (II) during hydrothermal synthesis and incorporated into the silicalite-2 framework during calcination at 500 degrees C. Further calcination at 750 degrees C does not affect the crystallinity but oxidizes essentially all of the Mn (II) to Mn (III) in the framework. The large difference in oxidation temperatures between the II and III oxidation states provides a means of producing relatively pure manganese(II) and manganese(III) silicalite-2 materials for applications such as catalysis.     

Synthesis of 1,4-benzodiazepine-3,5-diones

Even though benzodiazepines have a strong position in medicinal chemistry, very few synthetic routes to 1H-1,4-benzodiazepine-3,5(2H,4H)-diones have ever been published and the claimed products have often been poorly characterized. Through the present work several 1H-1,4-benzodiazepine-3,5(2H,4H)-diones have become available from N-carbamoylmethylanthranilic acids. The required ring closures were achieved only when the amino groups of the starting materials were substituted with electron withdrawing groups such as acetyl, alkyloxycarbonyl, or nitroso. During the synthetic work a novel ring contraction rearrangement from a 1-nitroso-1H-1,4-benzodiazepine-3,5(2H,4H)-dione to a 3H-quinazoline-4-one was observed. The proposed mechanism involves elimination of HNO followed by a proton-mediated loss of CO. The 1-nitrosated 1,4-benzodiazepinediones could be separately denitrosated to the corresponding amino compounds.     

A Convenient Synthesis of 3,5-bis(Trifluoromethyl)Salicylic Acid

A convenient method is reported for the synthesis of the biologically important intermediate, 3,5-bis(trifluoromethyl)-salicylic acid, by a sequence involving diazotization/iodination of 2-bromo-3,5-bis(trifluoromethyl)aniline, displacement of the bromide with sodium methoxide, and carboxylation of the anion generated by lithium-iodine exchange with carbon dioxide. Alternatively, the anion could be carbonylated with dimethylformamide and the resulting aldehyde oxidized with Jones reagent. Demethylation of 3,5-bis(trifluoromethyl)anisic acid with boron tribromide gave the title compound.     

Synthesis and stereodynamics of highly constrained 1,8-bis(2,2'-dialkyl-4,4'-diquinolyl)naphthalenes (2)

Axially chiral 1,8-bis(2,2'-diphenyl-4,4'-diquinolyl)naphthalene, 8, and 1,8-bis(2,2'-diisopropyl-4,4'diquinolyl)naphthalene N,N'-dioxide, 9, have been prepared to study the stereodynamics of these and other 1,8-diheteroarylnaphthalenes based on reversible first-order isomerization kinetics and crystallographic data. The ratio of the two enantiomeric anti-conformers to the meso syn-isomer of 8 and 9 was determined as 1.2:1 and 9.6:1. Investigation of the conformational stability of the atropisomers at enhanced temperatures using HPLC and NMR spectroscopy revealed a Gibbs activation energy of 122.4 (121.8) kJ/mol and 115.2 (109.0) kJ/mol for the anti/syn- (syn/anti)-isomerization of 8 and 9, respectively. Comparison of the conformational stability of a series of 1,8-dipyridylnaphthalenes and 1,8-diquinolylnaphthalenes shows that the latter exhibit a significantly higher rotational energy barrier. While the syn- and anti-isomers of 1,8-dipyridylnaphthalenes interconvert rapidly at room temperature the stereoisomers of 1,8-diquinolylnaphthalenes can be isolated by chromatography or crystallization and stored at 25 degrees C for several months without any sign of racemization. The conformational stability of 1,8-diquinolylnaphthalenes is a consequence of significantly increased steric hindrance to isomerization in a highly congested T-shaped transition state. Conversion of 1,8-diheteroarylnaphthalenes to their corresponding N,N'-dioxides was found to result in an increased anti/syn-ratio and decreased rotational energy barrier, which was attributed to synergistic repulsive dipole/dipole interactions destabilizing the diastereomeric ground states and facilitated out-of-plane bending reducing the steric hindrance in the T-shaped transition state.     

Synthesis and Pyrolysis of Tetrahydro-1,4-oxazine-3,5-diones and Tetrahydro-1,4-thiazine-3,5-diones

The preparation and characterization of six 4-substituted tetrahydro-l,4-oxazine-3,5-diones and five 4-substituted tetrahydro-l,4-thiazine-3,5-diones is described. Upon flash vacuum pyrolysis at 700°C these give N-substituted acetamides and nitriles, and a mechanism for formation of these products is proposed.     

Synthesis and polymorphism evaluation of the 3,5-bis(decyloxy)benzaldehyde

In this work, 3,5-bis(decyloxy)benzaldehyde, a precursor of long chain amphiphilic BODIPYs, was synthesized and its polymorphic behavior was characterized by differential scanning calorimetry, polarized light thermo microscopy, infrared spectroscopy, and XRPD. From the combined use of these techniques, an interesting polymorphic behavior was observed, and four polymorphs were identified. The initial compound melts around room temperature, ca. 30 °C, and several polymorphic forms of lower melting point are obtained by cooling the melt. A thermal program could be developed that allows obtaining each form independently.     

Synthesis and calculated properties of some 1,4-bis(amino)anthracene-9,10-diones

The synthesis of a number of 1,4-bis(amino)anthracene-9,10-diones containing chlorine or sulfur which are related to the anti-cancer drugs Ametantrone and Mitoxantrone are reported. 1,4-Dichloro-2,3-dihydro-5,8-dihydroxyanthracene-9,10-dione reacts readily with a series of alkylamines to yield the corresponding 1,4-bis(alkylamino)-5,8-dichloroanthracene-9,10-dione after oxidation. The subsequent reaction of the products with ethanethiol or thiophenol gives the corresponding 1,4-bis(alkylamino)-5,8-bis(sulfanyl)anthracene-9,10-dione in good yield. Theoretical calculations at the RHF 6-31G** level indicate that the introduction of either chlorine or the phenylsulfanyl group into the 5- and 8-positions of 1,4-bis(alkylamino)anthracene-9,10-diones results in a lowering of the LUMO energies suggesting that related functionalised derivatives might have lower cardiotoxicities than Mitoxantrone.     

Synthesis and Crystal Structure of 2,6-Bis（2-pyridinylmethyl）-3,5-bis（2-hydroxyl-5-chlorophenyl）pyrazine

The title compound,2,6-bis(2-pyridinylmethyl)-3,5-bis(2-hydroxyl-5-chlorophe nyl)-pyrazine(C26H12Cl2N4O2C2H8O2,Mr=551.41),has been synthesized and characterized by LC-ESIMS,NMR,UV and IR spectroscopy as well as by X-ray single-crystal diffraction.The compound behaves as a substituted pyrazine.The hydrogen atoms on C(2) and C(3) are substituted by 2-pyridinyl,whereas those on C(1) and C(4) are substituted by 2-hydroxyl-5-chlorophenyl.It crystallizes in the monoclinic system,space group P21/c with a=8.9433(12),b=32.003(4),c=10.5209(18),β=111.199(2)°,V=2807.5(7)3,Z=4,Dc=1.305 mg/m3,F(000)=1144 and μ=0.094 mm-1.A total of 13235 reflections were collected in the range of 2.17～25.01o by using a phi and omega scan mode,of which 4923 were unique(Rint=0.0692) and 2872 observed reflections with Ⅰ > 2σ(Ⅰ) were used in the structure solution and refinement.     

Synthesis of 4-substituted 1,4-benzodiazepine-3,5-diones

Synthetic routes leading to the preparation of 4-substituted 1,4-benzodiazepine-3,5-diones are described. Thus, 2-carbobenzoxyaminobenzoic acid was converted to its p-nitrobenzyl ester (I) and the decarbobenzoxylated product (II) gave, with ethyl α-bromoacetate, N-(2-carboxy p-nitrobenzylate)phenylglycine ethyl ester (III). The latter was hydrogenolyzed to N-(2-car-boxy)phenylglycine ethyl ester (IV), which was coupled with benzylamine to give N-(2-carboxy-benzylamido)phenylglycine ethyl ester (VIa). Saponification of VIa afforded N-(2-carboxy-benzylamido)phenylglycine (VIIa) which was cyclized with DCCI to produce 4-benzyl-2H-1,4-benzodiazepine-3,5(lH,4H)dione (VIIIa). Alternatively, 2-nitro-N-phenylbenzamide (Xb) was reduced to 2-amino-N-phenylbenzamide (XIb) which was converted to N-(2-carboxanih'do)-phenylglycine ethyl ester (VIb). The latter was converted to 4-phenyl-2H-1,4-benzodiazepine-3,5(1H,4H)dione (VIIIb) in an analogous fashion described for VIIIa.     

Synthesis of bis(diethyldithiocarbamato)manganese(II) and tris(diethyldithiocarbamato)manganese(III)

An ideal undergraduate introduction to the challenges of synthesis and characterization of air-sensitive compounds is accomplished in the preparation of bis(diethyldithiocarbamato)manganese(II). This economical experiment employs a glovebag, low-cost and low-toxicity chemicals, and is completed in one undergraduate laboratory period. For comparison purposes, the synthesis and characterization of air-stable tris(diethyldithiocarbamato)manganese(III) is also described.     

Synthesis of 2-substituted indoles by iridium (III)-catalyzed CH functionalization of N-phenylpyridin-2-amines

A highly regioselective synthesis of 2-substituted indoles was realized through Ir(III)-catalyzed CH functionalization of N-phenylpyridin-2-amines followed by the reaction with sulfoxonium ylides and intramolecular cyclization under mild conditions. The reaction completed with broad range of substrate scopes and gave various 2-substituted indoles in up to 98% yields.     

Scandium(III)-catalyzed enantioselective allylation of isatins using allylsilanes

The scandium(III)-catalyzed enantioselective Hosomi-Sakurai allylation of isatins with various substituted allylic silanes is described. A catalyst loading as low as 0.05 mol % is utilized at room temperature to afford the 3-allyl-3-hydroxy-2-oxindoles in excellent yields and enantioselectivity up to 99% ee, including a demonstration of a gram-scale reaction. The effects of additives and varying silyl groups were explored to demonstrate the scope and application.     

Crystal structure of 4,4-bis(2′-hydroxyethyl)-morpholinium picrate

Institute of Physiologically Active Substances, Academy of Sciences of the USSR, Chernolovka. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 5, pp. 174–177, September–October, 1988.     

Synthesis of derivatives of α-phenyldinicotinic acid and 2-phenyl-3,5-bis(5-phenyl-2-oxazolyl)-pyridine

The dichloride, diethylamide, and amide were obtained from -phenyldinicotinic acid. 2-Phenyl-3,5-diamino- and 3,5-dicyanopyridine were synthesized from the amide. 2-Phenyl-3,5-bis(5-phenyl-2-oxazolyl)pyridine and 2-phenyl-3-carboxy-5-(5-phenyl-2-oxazolyl)pyridine were obtained. The luminescence properties of the synthesized compounds were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 405–411, March, 1990.The authors thank A. A. Ustenko and E. N. Smirnova for their assistance in calculation of the spectral data.