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《催化学报》2017,(10)
含硫化合物在有机合成、药物化学以及材料化学等领域具有重要的作用.到目前为止,科学家已经在C-S键的构建领域进行了很多工作.在构建C-S键的众多方法中,金属催化的C-S键合成反应是一类很重要的反应,但是此方法存在着催化剂对空气敏感、环境不友好等问题.因此,发展无金属催化的C-S键构建反应受到了人们越来越多的重视.基于我们在碘催化相关反应方面的研究,本文报道了一种碘催化的硫化吡唑啉酮类化合物的合成方法.我们选用3-甲基-1-苯基-2-吡唑啉-5-酮与二苯二硫醚为底物进行条件筛选实验,发现I_2(10%)为催化剂,二氧六环为溶剂,H_2O_2为氧化剂为最优化的实验条件,目标产物硫化吡唑啉酮最高产率为88%.在最优化的反应条件下,我们尝试了带有不同官能团(NO_2,Cl,OH等)的吡唑啉酮与二硫醚的反应,均能以较高产率得到目标产物.当含有杂环的二硫醚(2,2'-二硫二吡啶)作为反应底物时,也能以中等以上的产率得到相应的目标产物.另外还进行了对比试验,例如在反应体系中加入自由基捕获剂TEMPO,反应产率会大大降低,说明反应中应该有自由基中间体生成;如果反应体系中不加碘,则反应产率为零;如果反应体系中不加H_2O_2,则反应产率由88%降低至48%,说明碘和H_2O_2在反应中都起到了重要作用.通过以上对比试验,提出了可能的反应机理:首先,二硫醚发生均裂反应生成苯硫基自由基,然后苯硫基自由基与碘反应生成亲电的PhSI活性中间体,PhSI与异构化的吡唑啉酮发生亲电取代反应,生成目标产物硫化吡唑啉酮和HI,HI可以被H_2O_2氧化生成I_2继续参与下一轮催化反应.以3-甲基-1-苯基-2-吡唑啉-5-酮与二苯二硫醚为底物,我们对此反应进行了放大试验,结果显示反应产率几乎没有降低,这为此反应的大规模应用奠定了基础.在此,我们发展了一种简单高效的合成硫化吡唑啉酮的反应,此方法无需金属催化剂,利用常见的碘为催化剂就可以以较高的产率得到目标产物.为合成含硫化合物提供了一种新的方法 相似文献
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通过表面增强拉曼光谱(SERS)与高效液相色谱(HPLC)联用开展了在线监测催化剂对邻氨基苯硫酚(OATP)与邻碘苯甲酰氯反应的影响. 结果表明, 无催化剂时反应产物为1b{S-[2-(2碘苯甲酰氨基)苯基]-2-碘代苯硫酸盐}和2b{N,N′-[二硫(2, 1-亚苯基)]二(2-碘苯甲酰胺)}, 在醋酸铜催化下生成3b{10-(2-碘苯甲酰基)二苯并[b, f ][1, 4]硫氮杂-11(10H)-酮}; 无催化剂条件下经历亲核取代反应及硫自由基耦合的过程, 在醋酸铜催化下产物 1b 的结构发生变异生成3b. 所得结果与核磁质谱等常规非现场技术解析结构一致. 相似文献
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Villemin[1]曾报道KSF/蒙托土催化下微波促进1-苯基-3-甲基-5-吡唑啉酮(1)与醛2的缩合反应,李晓陆[2研究了该反应的固相缩合,Sun[3]报道了KF-Al2O3催化下甲醇溶液中的反应.本文采用绿色合成原则,无催化剂条件下无溶剂微波辐射及水中回流方法研究了此反应,得到两类化合物(图1).产物结构经1H NMR,13C NMR,MS及IR确证.实验发现辐射功率对产物有很大影响,高辐射功率下得到4-芳甲叉-3-甲基-1-苯基-5-吡唑啉酮(3),低辐射功率得到4,4′-芳甲叉-双(3-甲基-1-苯基-5-吡唑啉酮)(4);水相反应同时得到两种产物,以产物3为主(表1).产物结构与反应物配比无关. 相似文献
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以二苯二硫醚为硫源,在无强碱和配体的条件下,通过碘化亚铜催化促进S—S键断裂,再与苯并五元杂环化合物反应生成了芳基硫醚,采用1H NMR和13C NMR对目标化合物进行了表征,并确定了最佳反应条件.在苯并五元杂环化合物和二苯二硫醚的物质的量比为2∶1,催化剂Cu I用量为10 mol%,溶剂为二甲基亚砜(DMSO),反应温度110℃,时间12 h时,产率达到89.9%.同时,通过高效液相色谱(HLPC)进行跟踪监测,对该反应的机理进行了探讨. 相似文献
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A convenient one-pot procedure for the preparation of pyrazoles by 1,3-dipolar cycloaddition of diazo compounds generated in situ has been developed. Diazo compounds derived from aldehydes were reacted with terminal alkynes to furnish regioselectively 3,5-disubstituted pyrazoles. Furthermore, the reaction of N-vinylimidazole and diazo compounds derived from aldehydes gave exclusively 3-substituted pyrazoles in a one-pot process. 相似文献
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Dr. Carlos Vila Fares Ibrahim Amr Prof. Dr. Gonzalo Blay Prof. Dr. M. Carmen Muñoz Prof. Dr. José R. Pedro 《化学:亚洲杂志》2016,11(10):1532-1536
An efficient one‐pot asymmetric synthesis of pyrazoles bearing a chiral quaternary stereocenter has been developed. Quinine‐derived thiourea catalyzed the enantioselective addition of pyrazolones to isatin‐derived ketimines, providing the corresponding acetylated pyrazoles after in situ treatment with Ac2O/Et3N. The corresponding pyrazoles were afforded in high yields and excellent enantioselectivities. 相似文献
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Hai-Ling Liu Min Zhang Wen-Juan Yao Qiu-Hua Zhu Zhou Tang 《Tetrahedron letters》2008,49(23):3805-3809
An efficient and general one-pot procedure for the synthesis of pyrazoles from acid chlorides, terminal alkynes and hydrazines was described via a coupling and cyclocondensation sequence. Acid chlorides coupled with terminal alkynes to give α,β-unsaturated ynones, and in situ converted into pyrazoles by the cycloaddition of hydrazines. The desired pyrazoles were obtained with 15-85% isolated yields. 相似文献
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Rapid parallel liquid-phase synthesis of pyrazoles has first been developed. The 1,3-dipolar cycloaddition between nitrilimines generated in situ and soluble polymer-supported alkynyl or alkenyl dipolarophiles in parallel one-pot fashion gave the corresponding PEG-supported regioisomeric pyrazoles or regiospecific pyrazolines. The latter was assuredly oxidated by DDQ to PEG-supported regiospecific pyrazoles. Cleavage from the support under mild conditions afforded pyrazoles in good yields and high ouritv. 相似文献
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[reaction: see text] 1,3-Diketones were synthesized directly from ketones and acid chlorides and were then converted in situ into pyrazoles by the addition of hydrazine. This method is extremely fast, general, and chemoselective, allowing for the synthesis of previously inaccessible pyrazoles and synthetically demanding pyrazole-containing fused rings. 相似文献
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The syntheses of an important class of hitherto unreported novel pyrazoles are described. The regioselective synthesis of 1,3,4,5-tetrasubstituted pyrazoles was achieved by the Huisgen cyclization of nitrile imines with a trisubstituted bromoalkene. The substituted bromoalkene functions as an alkyne synthon which was used to construct 5,5-disubstituted bromopyrazoline intermediates that undergo aromatization to the analogous pyrazoles through the loss of HBr. The cycloaddition regioselectivity was confirmed through single X-ray crystal data of one of the pyrazoles. 相似文献
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Supramolecular Columnar Liquid Crystals with Tapered‐Shape Simple Pyrazoles Obtained by Efficient Henry/Michael Reactions 下载免费PDF全文
Hugo Blanco Verónica Iguarbe Prof. Joaquín Barberá Prof. José Luis Serrano Dr. Anabel Elduque Dr. Raquel Giménez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4924-4930
A straightforward synthesis of mesogenic pyrazoles starting from benzaldehydes by a combination of efficient Henry and Michael reactions led to novel supramolecular liquid crystals. The mesogens are fluorescent 3,5‐dimethyl‐4‐(di or trialkoxyphenyl)pyrazoles and, in spite of the tapered shape of these molecules and their structural simplicity (only one phenyl ring), columnar liquid‐crystal phases were formed that are stable at room temperature. The self‐assembled structure was studied by XRD and the columnar cross section contains two molecules on average with an antiparallel arrangement of pyrazoles interacting through hydrogen bonds. In contrast, the single‐crystal structure of a trimethoxy analog did not show hydrogen‐bonded pyrazoles but chains of head‐to‐tail arranged molecules. 相似文献
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Directing/Protecting‐Group‐Free Synthesis of Tetraaryl‐Substituted Pyrazoles through Four Direct Arylations on an Unsubstituted Pyrazole Scaffold 下载免费PDF全文
Dr. Shinichiro Fuse Taiki Morita Dr. Kohei Johmoto Dr. Hidehiro Uekusa Dr. Hiroshi Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14370-14375
A directing/protecting‐group‐free synthesis of 1,3,4,5‐tetraaryl‐substituted pyrazoles was achieved through four transition metal‐catalyzed direct arylations. Various pyrazoles with four different aryl rings were obtained using readily available reagents from an unsubstituted pyrazole. Two aryl‐substituted pyrazoles showed intense violet fluorescence, high quantum yields (Φf=0.68, 0.64), and large Stokes shifts (19000, 15200 cm?1). 相似文献
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This review introduces the synthesis of various pyrazoles reported by us and some other research groups during 1989–1998. Some of papers in this review deal with the development of potent pyrazoles or with the synthesis of potential pyrazoles aiming at agrochemicals and/or drugs. 相似文献
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Ramsay E. Beveridge Dilinie Fernando Brian S. Gerstenberger 《Tetrahedron letters》2010,51(38):5005-5008
A straight-forward route to prepare a diverse set of N-aryl pyrazoles via a one-pot copper-catalyzed boronic acid coupling and cyclization protocol is presented. A variety of aryl and heteroaryl N-functionalized pyrazoles not easily accessible by other means were formed in good yield from readily available boronic acid precursors in an operationally simple procedure. 相似文献