Ethylcyclopentane ring opening reaction over PtGe/Al2O3 catalysts prepared by controlled surface reaction

Platinum-germanium catalysts supported on a non-acidic Al₂O₃ have been prepared by adding Ge in amounts corresponding nominally to 1/8 (PtGe1/8/Al₂O₃); 1/2 (PtGe1/2/Al₂O₃); 1 (PtGe1/Al₂O₃) and 2 (PtGe2/Al₂O₃) monolayers by controlled surface reaction of Ge(n-C₄H₉)₄ to Pt/Al₂O₃. These catalysts were characterized by electron microscopy (TEM), FTIR of CO adsorption and H₂ chemisorption. The ring opening of ethylcyclopentane (ECP) was studied as a test reaction between 543 and 633 K. PtGe1/8/Al₂O₃ catalyst produced the most ring opening products (ROP) in the whole temperature range. A good agreement with statistical values of ROP was observed at low temperature, but at higher temperature, the opening became selective, producing mostly heptane. Bimetallic catalysts PtGe1/Al₂O₃ and PtGe2/Al₂O₃ led to a nonselective hydrogenolysis, similar to the monometallic platinum catalyst Pt/Al₂O₃. The catalysts PtGe1/Al₂O₃ and PtGe2/Al₂O₃ produced ROP with the lowest selectivity; instead, much aromatics and fragments were formed, in increasing amounts above 600 K.     

金属催化二氯化物RCCl_2CH_2CH_2R~1合成反应的研究

在醇溶剂中，用金属或金属合金作为反应的催化剂，多氯化物RCCl_3和含吸电 子基的末端烯烃CH_2=CHR~1反应一步生成RCCl_2CH_2CH_2R~1。在此反应中，加成 反应和脱氯反应一步完成。     

Preparation of α- or β-trifluoromethylated vinylstannanes and their cross-coupling reactions

α- or β-Trifluoromethylated vinylstannanes 1, 2a, 3 and 4 were prepared form 1,1-bis(phenylthio)-2,2,3,3,3-pentafluoropropylbenzene (5) via several steps. The cross-coupling arylation reactions of 1–4 with aryl iodides bearing a bromo, methoxy, methyl, nitro or trifluoromethyl group on para- or meta-position of benzene ring afforded the corresponding coupling products in good yields. Compounds 1, 2a and 4 underwent the acylation reaction with various types of acyl chlorides to give the corresponding trifluoromethylated enone derivatives in good yields. Reduction of trifluoromethylated enone derivatives with LiAlH₄, followed by Fridel-Craft’s type of cyclization with AlCl₃ provided trifluoromethylated indene derivatives in good yields.     

3-Benzoylquinoxalin-2(1H)-one in the Kostanecki-Robinson Reaction. Synthesis and Structure of 2-Oxo-4-phenylpyrano[2,3-b]quinoxaline

3-Benzoylquinoxalin-2(1H)-one is cyclized with acetic anhydride in the presence of pyridine into 2-oxo-4-phenylpyrano[2,3-b]quinoxaline.     

1-取代胺甲基-7,8-二去氢-4-羟基-3,7-二甲氧基-17-甲基-9α,13α,14α-吗啡烷-6-酮的合成

超声波辐射下, 以盐酸青藤碱为原料, 在其A环1-位碳上进行Mannich反应, 合成了2个新的取代胺甲基化合物 1a, 1b. 且由化合物1a与取代芳胺及吗啉通过胺交换反应合成了8个新的取代胺甲基化合物2a～2h. 所有新化合物的结构利用IR, MS, ¹H NMR及NOE差谱进行了表征.     

五甲基-2-噻吩基二硅烷的光解反应

本文研究了五甲基-2-噻吩基二硅烷的光解反应, 反应以环乙烷为溶剂, 乙醇作为捕捉剂, 主要产物是二甲基-2-噻吩基硅烷, 三甲基-2-噻吩硅烷, 三甲基乙氧基硅烷和二甲基乙氧基硅烷。     

基于芳叉丙二腈的高活性迈克尔系统的吸湿反应及荧光性质

建立了一个基于芳叉丙二腈的高活性迈克尔系统2,2′-[(5-叔丁基-2-羟基-1,3-苯撑)二甲川]双丙二腈(1), 能迅速吸收空气中的水, 生成稳定的氧杂迈克尔加成产物2-[5-叔丁基-3?(2,2-二腈基?1-羟乙基)-2-羟基苄叉]丙二腈(2). 在二甲亚砜(DMSO)中, 各种碱性催化剂都能使化合物2脱水生成化合物1, 同时发射红色强荧光. 在PBS缓冲溶液(pH=10)中, 化合物2立即脱水生成化合物1, 随后又缓慢加水转变为化合物2. 加热吸附在硅胶上的化合物2的荧光由蓝色变为红色, 温度降低后荧光又恢复为蓝色. 因此, 吸附了化合物2的硅胶可能发展成为一种热敏荧光材料. 此外, 吸附了化合物1的硅胶还对某些有机蒸汽具有荧光响应.     

Stereoselective oxidative addition of benzenethiol to idene in the presence of ovoalbumin

The oxidative addition of benzenethiol to indene in the presence of ovoalbumin produces only one isomer on the surface of the protein,trans-anti-2-phenylsulfinyl-1-indanol. This reaction may be considered as a biomimetic model of detoxification of certain hydrocarbons by the liver.

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Stereoselektive oxydative Anlagerung von Thiophenol an Inden in Gegenwart von Ovoalbumin (Kurze Mitteilung)

Zusammenfassung Durch die oxydative Anlagerung von Thiophenol an Inden in Gegenwart von Ovoalbumin bildet sich nur ein Isomer an der Oberfläche des Proteins, dastrans-anti-2-Phenylsulfinyl-1-Indanol. Diese Reaktion kann als ein biomimetisches Modell der Entgiftung von gewissen Kohlenwasserstoffen durch die Leber betrachtet werden.

     

Synthesis of the dibenzo[f,h]phthalazine and dibenzo[f,h]cinnoline skeleton via a ‘Suzuki-Pd-catalyzed intramolecular arylation’ and a ‘Suzuki-Pschorr’ approach

Palladium-catalyzed intramolecular arylation of 2-benzyl-5-(2-bromophenyl)-4-phenylpyridazin-3(2H)-one yielded hitherto unknown 2-benzyldibenzo[f,h]phthalazin-1(2H)-one. The synthesis of this new tetracyclic pyridazinone from 2-benzyl-5-(2-aminophenyl)-4-phenylpyridazin-3(2H)-one via a Pschorr type reaction was also investigated. Similarly, the construction of 2-methyldibenzo[f,h]cinnolin-3(2H)-one from 2-methyl-5-(2-bromophenyl)-6-phenylpyridazin-3(2H)-one and 2-methyl-5-(2-aminophenyl)-6-phenylpyridazin-3(2H)-one is also reported. Removal of the N-benzyl protective group of 2-benzyl-dibenzo[f,h]phthalazin-1(2H)-one with AlCl₃ yielded unsubstituted dibenzo[f,h]phthalazin-1(2H)-one.     

Simple access to pentacyclic oxazinoisoquinolines via an unexpected transformation of aminomethylnaphthols

Unexpected reactions between 1-α-aminobenzyl-2-naphthol, 1-aminomethyl-2-naphthol, N-benzyl-1-α-aminobenzyl-2-naphthol and 6,7-dimethoxy-3,4-dihydroisoquinoline to furnish naphth[1,2-e][1,3]oxazino[2,3-a]isoquinolines are reported. The reaction conditions involved classical heating at 80 °C in MeCN for 22 h (57-62%), or the use of microwave conditions (100 °C), which allowed a reduction of the reaction time to 90 min and resulted in somewhat higher yields (73-82%).     

Theoretical study of the electrocyclic ring closure of hydroxypentadienyl cations

At the 6-311G* level of theory, DFT methods predict that the rearrangement of 1,4-dihydroxy-5-methylpentadienyl cation 1 (R = Me) to protonated trans-3-hydroxy-2-methylcyclopent-4-en-1-one 2, an intermediate step in the Piancatelli reaction or rearrangement of furfuryl carbinols to trans-2-alkyl(aryl)-3-hydroxycyclopent-4-en-1-one, is a concerted electrocyclic process. Energetic, magnetic, and stereochemical criteria are consistent with a conrotatory electrocyclic ring closure of the most stable out,out-1 isomer to afford trans-2. Although the out,in-1 isomer is thermodynamically destabilized by 6.84 kcal mol(-1), the activation energy for its cyclization is slightly lower (5.29 kcal mol(-1) versus 5.95 kcal mol(-1)). The cyclization of the isomers of 1 with the C1-hydroxy group inwards showed considerably higher activation energies than their outwards counterparts. in,out-1, although close in energy to out,out-1 (difference of 1.57 kcal mol(-1)) required about 10 kcal mol(-1) more to reach the corresponding transition structure. The value measured for the activation energy of in,in-1 (17.32 kcal mol(-1)) eliminates the alternative conrotatory electrocyclization of this isomer to provide trans-2. Geometric scrambling by isomerization of the terminal C1--C2 bond of 1 is also unlikely to compete with electrocyclization. The possibility to interpret the 1-->2 reaction as a nonpericyclic cationic cyclization was also examined through NBO analysis, and the study of bond lengths and atomic charges. It was found that the 1-->2 concerted rearrangement benefits from charge separation at the cyclization termini, an effect not observed in related concerted electrocyclic processes, such as the classical Nazarov reaction 3-->4 or the cyclization of the isomeric 2-hydroxypentadienyl cation 5.     

The perfluoroallylation of alkynes and transformation of the products

The addition of perfluoroallyl iodide to alkynes 1 initiated by AIBN in the absence of solvent 65 °C gave the corresponding 1:1 adducts (1,1,2,3,3-pentafluoro-5-iodopenta-1,4-dienes) 2. The reaction of 2 with boronic acids 3 and terminal alkynes 1 in the presence of catalytic palladium afforded the cross-coupling products 4 and 5, respectively.     

Kinetics of the ene reactions of 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione with β‐pinene and 2‐carene: Temperature,high pressure,and solvent effects

The data on temperature, solvent, and high hydrostatic pressure influence on the rate of the ene reactions of 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione ( 1 ) with 2‐carene ( 2 ), and β‐pinene ( 4 ) have been obtained. Ene reactions 1 + 2 and 1 + 4 have high heat effects: ∆H_r‐n ( 1 + 2 ) −158.4, ∆H_r‐n( 1 + 4 ) −159.2 kJ mol⁻¹, 25°C, 1,2‐dichloroethane. The comparison of the activation volume (∆V^≠( 1 + 2 ) −29.9 cm³ mol⁻¹, toluene; ∆V^≠( 1 + 4 ) −36.0 cm³ mol⁻¹, ethyl acetate) and reaction volume values (∆V_r‐n( 1 + 2 ) −24.0 cm³ mol⁻¹, toluene; ∆V_r‐n( 1 + 4 ) −30.4 cm³ mol⁻¹, ethyl acetate) reveals more compact cyclic transition states in comparison with the acyclic reaction products 3 and 5 . In the series of nine solvents, the reaction rate of 1+2 increases 260‐fold and 1+4 increases 200‐fold, respectively, but not due to the solvent polarity.     

Regioselective synthesis of 2,3-disubstituted 1-alkyl pyrrolo[2,3-b] quinoxalines through palladium-catalyzed Heck reaction of chalcones and evaluation of their anti-bacterial activities

The regioselective synthesis of 1-alkyl-2-aryl-3-acyl pyrrolo[2,3-b]quinoxalines through palladium-catalyzed Heck coupling reaction/heteroannulation was reported. The reaction of N-alkyl/benzyl-3-chloroquinoxaline-2-amines with chalcones catalyzed by Pd(OAc)₂ in the presence of KO^tBu, as the base, in DMSO afforded the desired products in good-to-high yields. The MIC and MBC determinations revealed that these compounds could be used in the future research works for the development of antibiotics.     

两种新型丁二炔衍生物的合成

以3,5-二溴-1-｛3-（十二烷氧基）-2-［（十二烷氧基）甲基］丙氧基｝苯和2-甲基-3-丁炔-2-醇为原料,经选择性Sonogashira偶联反应,Sonogashira偶联反应和去硅保护基反应制得中间体--3-乙炔基-5-（3-甲基-3-羟基)-丁炔基-1-（3-十二烷氧基）-2-｛［（十二烷氧基）甲基］丙氧基｝苯（6）; 6经改良的Glaser偶联反应(CuI为催化剂,Et₃N为溶剂)合成了一个新型的丁二炔衍生物（1）。 6与2,2′-［（2,5-二碘-1,4-亚苯基）双（氧基）］双（四氢-2H-吡喃）经Sonogashira偶联,脱 THP保护基和改良的Glaser偶联反应合成了一个新型的丁二炔衍生物（2）。中间体,1和2的结构经¹H NMR, ¹³C NMR和MALDI-TOF-MS表征。     

(C6H8N3)+I3-和[(Cu3I4)(C8H17N2)]配体原位合成与结构表征

在溶剂热条件下, 以原位反应为基础合成了两个碘化物(C6H8N3)+I3-(1, C6H8N3=2,3-dihydroimi-dazo[1,2-a]pyrimidin-1-ium, 2,3-二氢咪唑[1,2-α]-嘧啶鎓阳离子)和[(Cu3I4)(C8H17N2)](2, C8H17N2=N-ethyl-4-aza-1-azonia-bicyclo[2.2.2]octane, N-乙基三乙烯二铵阳离子). 用元素分析、粉末X射线衍射及单晶X射线衍射等对化合物进行了表征. 结果表明, 化合物1属于三斜晶系, P1空间群, a=0.74281(15) nm, b=0.84241(17) nm, c=0.9993(2) nm, α=82.02(3)°, β=83.30(3)°, γ=82.92(3)°, V=0.6114(2) nm3. 化合物2属于单斜晶系, P21/c空间群, a=0.68924(14) nm, b=1.0786(2) nm, c=2.2779(5) nm, β=94.84(3)°, V=1.6874(6) nm3. 在两个化合物合成中存在两种不同类型的配体原位合成反应, 即化合物1的2-氨基嘧啶和乙醇的成环反应与化合物2的三乙烯二胺和乙醇的烷基化反应.     

Kinetic scheme of homogeneous acid-catalyzed transformation of isopentenols

The reactions occurring in an equilibrium mixture of 3-methyl-1-buten-3-ol and 3-methyl-2-buten-1-ol in 24–49 % aqueous solutions of H₂SO₄ yield isoprene, 3-methyl-3-buten-1-ol, isobutylene, formaldehyde, 3-methylbutane-1,3-diol. Isobutylene is rapidly hydrated to give 2-methylpropan-2-ol. The presence of formaldehyde in the reaction mixture indicates that the transformations involve the reverse Prins reaction. On the basis of experimental and literature data, two most probable reaction schemes were suggested.Translated fromIzvestiya Akademii Nauk. Sertya Khimicheskaya, No. 5, pp. 867–870, May, 1995.     

Exceptional molecular architectures via cycloadditions to pyrenequinones

The thermal reaction of phencyclone (2) with a 1:1 mixture of 1,8-pyrenequinone (4) and 1,6-pyrenequinone (5) yields 2:1 adducts only of compounds 2 and 4. The observed polycyclic aromatic hydrocarbon 8 is formed via double Diels-Alder addition of 2 to 4, and the polycyclic ketone 9 arises from a combination of Diels-Alder and hetero-Diels-Alder reactions of 2 and 4. In contrast, Lewis acid-catalyzed reactions of 2, 4, and 5 give 2:1 adducts only of 2 and 5. The chief product, polycyclic diketone 10, is derived from a double hetero-Diels-Alder addition of 2 to 5. X-ray analysis of compound 8 shows it to be an exceptionally large polycyclic aromatic arch, and the X-ray structure of 10 reveals it to be a chiral molecular tweezer.     

微波辐射促进选择性合成4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮和嘧啶-2(1H)-酮

探讨了在微波加热条件下,芳香醛、取代苯乙酮和尿素的三组分反应在N,N-二甲基甲酰胺(DMF)中制得4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮类化合物,收率为68%～84%.若在反应体系中加入三甲基氯硅烷,该三组分反应则高产率(66%～87%)地生成相应的脱氢产物4,6-二芳基嘧啶-2(1H)-酮类化合物.该反应具有反应条件温和、产物收率高、操作方便等优点,为4,6-二芳基-嘧啶-2(1H)-酮类药物中间体的合成提供了一条全新的路线.     

Photoinitiated Reaction of β-Bromonaphthalene with Pinacolone Ion in DMSO

The radical nucleophilic substitution reaction (SRN1) has been studied widely. The reaction has constituted an important synthetic possibility to achieve substitution of different substrates with different nucleophiles1-3. The main steps of the reaction process are presented in Scheme 1.Scheme 1. Pinacolone enolate ions are widely used as nucleophiles within SRN1reaction 4-6 because it can introduce six carbon atoms into substitution products. In the paper, the photoinitiated reaction of …