催化量碘代烷烃促进下合成3,5-二取代异噁唑啉

研究了端基烯烃和醛肟在氧化剂过硫酸氢钾和催化量碘代烷烃作用下的[3+2]环合反应,合成了一系列具有良好产率及区域选择性的3,5-二取代异噁唑啉化合物.反应中,碘代烷烃先经过氧化分解产生了活泼的次碘酸,再依次与醛肟和烯烃经亲电加成反应生成五元杂环碘代中间体,该中间体通过消除反应得到3,5-二取代异噁唑啉化合物.考察了反应条件的影响,提出了可能的反应机理,为合成3,5-二取代异噁唑啉化合物提供了新方法.     

2,5-二取代基-1,3,4-噁二唑及噁二唑啉类化合物的合成

2-苯基-1,2,3-连三唑-4-甲酰肼(1)与芳酸在POCl_3催化下得到6种新的2-芳基-5-(2’-苯基-1’,2’,3’-连三唑-4’-基)-1,3,4-噁二唑(2)。1与羰基化合物缩合得到相应的酰腙(3),在Ac_2O作用下环化成2-取代基-3-乙酰基-5-(2’-苯基-1’,2’,3’-连三唑-4’-基)-1,3,4-噁二唑啉(4)。化合物的结构经元素分析,IR,~1H NMR和MS确证。     

含异噁唑环的新型2,5-二取代-1,3,4-噁二唑的合成及其杀菌活性

以取代异噁唑甲酸乙酯为起始原料,经取代、加成与环化反应合成了5个新型2-取代苯胺基-5-(取代异噁唑-4-基)-1,3,4-噁二唑(5a～5e),产率54.0％～86.7％,其结构经1H NMR,IR和元素分析表征.初步杀菌活性试验表明,5a,5c和5d对番茄灰霉病菌有很高的抑制作用,其活性高于对照药剂多菌灵.     

新型含异噁唑环1,3,4-噁二唑啉衍生物的合成

以N-羟基-4-甲氧基苯甲醛肟氯化物为原料,经两步反应制得3-对甲氧基苯基-5-甲基-异噁唑-4-甲酰肼(3);3依次经缩合和环合反应合成了一系列新型的2-芳基3-乙酰基-5-(3-对甲氧基苯基-5-甲基-异噁唑-4-基)-Δ4-1,3,4-噁二唑啉衍生物,其结构经~1H NMR,13C NMR,IR,MS(EI)和元素分析表征。     

聚乙二醇支持的2,5-二取代异噁唑啉衍生物的液相合成

介绍了通过1,3-偶极环加成合成2,5-二取代异噁唑啉衍生物的液相合成方法, 利用聚乙二醇(PEG)支持的烯烃与由醛肟制得的腈氧化物反应制备了多种异噁唑啉衍生物, PEG解脱后产物的产率和纯度均很高.     

一种有效合成3-芳基-4-氟烷基-2-噁唑烷酮的方法

报道了一种方便有效地合成3-芳基-4-氟烷基-2-噁唑烷酮的方法.用芳基胺作为起始原料通过与氯甲酸烯丙基酯反应以95.8%～99.5%的收率得到芳基氨基甲酸烯丙基酯.芳基氨基甲酸烯丙基酯与氟烷基碘在乙腈和水的混合液中由连二亚硫酸钠引发在室温下发生自由基加成反应得到氟烷基化的加成产物.加成产物在碱性条件下发生分子内的N-环合反应得到3-芳基-4-氟烷基-2-噁唑烷酮.整个反应都在室温下进行,并且没有用到光气合成了3-芳基-4-氟烷基-2-噁唑烷酮,该方法具有原料易得,条件温和,绿色环保的优点.     

新型异噁唑拼接三氟甲基螺环吡咯氧化吲哚类化合物的合成

以靛红衍生的三氟甲基亚胺与硝基异噁唑苯乙烯为原料,在有机碱DABCO催化作用下,发生[3+2]环加成反应,获得合成了15个新颖的异噁唑拼接三氟甲基螺环吡咯氧化吲哚类化合物3a~3o,产率71%~90%,dr值>20/1, 其结构经¹H NMR, ¹³C NMR和HR-MS（ESI-TOF）表征,化合物3f的相对构型通过单晶进一步进行了确定。该类化合物含有连续4个立体中心,包括一个螺环季碳中心。      

手性1,3,4-噁二唑硫醚衍生物的合成

以5-取代-2-巯基-1,3,4-噁二唑为亲核试剂,与手性5-烷氧基-3,4-二溴-2(5H)-呋喃酮发生Michael反应,合成了6种新的手性1,3,4-噁二唑硫醚衍生物(产率55%～67%),其结构经1H NMR, 13C NMR, IR和HR-MS确证.     

水相中3,5-二芳基异噁唑衍生物的微波辐射合成

微波辐射下,以芳香醛和芳香酮为起始原料合成2,4,6-三芳基吡喃盐,在NaOH水溶液中与盐酸羟胺发生开环、缩环和脱苯甲酰基反应,一步生成3,5-二芳基异噁唑衍生物。考察了微波辐射功率和辐射时间对目标产物收率的影响,2,4,6-三芳基吡喃盐与盐酸羟胺反应生成3,5-二芳基异噁唑衍生物的最佳微波辐射功率为600W,辐射时间为8min,最大收率为83%。该法不仅避免了使用高氯酸造成的环境污染,而且以水作为反应介质,使后处理简便。该工艺具有操作安全、反应条件温和和产率高等优点,是一种环境友好的合成工艺。产物经元素分析、1HNMR和MS测试技术表征了其结构。     

噁唑、苯并噁唑及1,3,4-噁二唑硫醚的合成及抗肿瘤活性研究

设计并以噁唑、苯并噁唑及1,3,4-噁二唑硫醇与卤代烃反应合成了14个硫醚类杂环化合物, 其中13个化合物未见文献报道. 目标化合物的结构均通过¹H NMR谱、MS和元素分析进行了表征. 采用MTT [3-(4,5-dimethylthiagol-2-yl)- 2,5-diphenyltetrogolium bromide]法对14个目标化合物进行了体外抗肿瘤活性测定, 结果表明: 在10^－5 mol/L 浓度下, 10个化合物对肿瘤细胞具有抑制活性.     

Novel formal [2+3] cycloaddition between substituted phenols and furan

Treatment of various substituted phenols in the presence of furan, iodobenzene diacetate, and trifluoroethanol promotes oxidative formal [2+3] cycloaddition in moderate to useful yields.     

An efficient chlorination of aromatic compounds using a catalytic amount of iodobenzene

An efficient method was developed for chlorination of aromatic compounds with electron-donating groups using iodobenzene as the catalyst and m-chloroperbenzoic acid as the terminal oxidant in the presence of 4-methylbenzenesulfonic acid in THF at room temperature for 24 h,and a series of the monochlorinated compounds was obtained in good yields.In this protocol,the catalyst iodobenzene was first oxidized into the hypervalent iodine intermediate,which then treated with lithium chloride and finally reacted with aromatic compounds to form the chlorinated compounds.     

An environmentally benign benzylic oxidation catalyzed by hypervalent iodine intermediate in water

An effective and environmentally benign benzylic oxidation for transition of alkylarenes into the corresponding carbonyl compounds was reported.Alkylarenes were mixed and stirred with potassium bromide,m-chloroperbenzoic acid and a catalytic amount of iodobenzene in water at 60 8C for several hours,a series of the corresponding carbonyl compounds was obtained in moderate to good yields.In the reaction,iodobenzene was first oxidized by m-chloroperbenzoic acid into the hypervalent iodine intermediate which then reacted with potassium bromide to form the key radical initiator for the benzylic oxidation.     

Synthetic studies of pestalotiopsin A: asymmetric synthesis of the 2-oxabicyclo[3.2.0]heptane substructure

A functionalized 2-oxabicyclo[3.2.0]heptan-3-one derivative, possessing all the skeletal carbons of pestalotiopsin A, has been synthesized. For the preparation of intermediary cyclobutane derivatives in enantioenriched form, the Lewis acid-catalyzed [2+2] cycloaddition of N-propiolated Oppolzer’s camphorsultam with dimethylketene bis(trimethylsilyl) acetal followed by a stereoselective 1,4-hydride addition/protonation, has been developed.     

The Regiospecific Synthesis of Some New 3,5‐Disubstituted Isoxazoles

The compounds with isoxazole moiety have many pharmacological, biological and industrial applications, specifically their antiviral activity. In this research work, seven new compounds of 3,5‐disubstituted isoxazoles were synthesized. Propargyl alcohol ( 1 ) reacted with benzoyl chloride to give propargylphenylcarboxylate ( 2 ). Then, the aldehydes ( 3a‐3g ) were converted to the related oximes ( 4a‐4g ) and nitrileoxides in situ by NaOCl, consequently. Reaction of compound 2 with nitrileoxides in a [3+2] cycloaddition reaction gave regiospecifically isoxazoles ( 5a‐5g ). ¹H NMR, ¹³C NMR, FT‐IR, and elemental analyses confirmed the structure of the synthesized compounds.     

1-氮杂-2,8-二氧杂二环[3.3.0]-辛烷类化合物合成的新方法

以苯基-3,5-二(甲氧基羰基)-2-异(口恶)唑啉-N-氧化物为偶极体,丙烯酸乙酯为亲偶极体,通过[3+2]环加成反应,简便地合成了含有多官能团的1-氮杂-2,8-二氧杂二环[3.3.0]-辛烷类化合物。该反应条件温和,产率较高(50%～93%).化合物的结构经元素分析,¹H NMR,¹³C NMR,IR和MS确认和表证,并对其波谱性质进行了讨论。     

Oxidative synthesis of azacyclic derivatives through the nitrenium ion: application of a hypervalent iodine species electrochemically generated from iodobenzene

Oxidation of the methoxyamide derivatives 1, 4, and 7 has been examined to elaborate efficient synthetic methodology of the azacyclic derivatives 2, 3, 5, 6, and 8, which would be applicable as synthetic intermediates of complicated bioactive substances. In addition to direct anodic and PIFA [phenyliodine(III) bis(trifluoroacetate)] oxidations, an active species derived from iodobenzene generated under electrolytic conditions was examined as an oxidant, and its synthetic efficacy was demonstrated in comparison of the reaction outcomes with other oxidation methods. In the oxidation, the methoxy substitution of substrates modulated the cyclization mode to provide the azaspiro- (2, 8) or quinolinone-type (3, 5, 6) products.     

A highly diastereoselective synthesis of 3-carbethoxy-2,5-disubstituted-3-pyrrolines by phosphine catalysis

Tributylphosphine was used as catalyst to facilitate a [3+2] cycloaddition between γ-substituted allenoates and N-sulfonylimines. The resulting adducts, 3-carbethoxy-2,5-disubstituted-3-pyrrolines, were formed in excellent yields with high diastereoselectivity. The reaction went to completion in several hours at room temperature, and the starting materials were easily prepared with one step from commercially available compounds via known procedures.     

Photochemical Experiments with 2,3-Bis(Tert-Butylsulfonyl)Bicyclo[2.2.2]Octa-2,5-Diene and Related Systems

The irradiation of 2,3-bis(tert-butylsulfonyl)norbornadiene (5) and 2-(tert-butylsulfonyl)norbornadiene (6) yielded the expected quadricyclane derivatives as stable molecules. The irradiation of 2,3-bis(tert-butylsulfonyl)bicyclo[2.2.2]octa-2,5-diene(7) 2,3-bis(tert-butylsulfonyl)-exo-7,8-epoxybicyclo[2.2.2]-octa-2,5-diene (8) and 8,9-bis(tert-butylsulfonyl)-4-anti-phenyl-3,5-dioxa-exo-tricyclo[5.2.2.0^2,6] undeca-8,10-diene 9a and its syn-isomer 9b yielded the corresponding tetracyclic and pentacyclic systems, respectively. The photoproducts of 8 and 9 reverted to the starting products slowly at room temperature. The half-life of the photoproduct of 7 was determined to be 34 min at 50 °C. Compound 9a reacted with n-BuLi to yield the unexpected desulfonylation product 27a.     

New synthetic methodology for 3-aminotropones

A new synthetic methodology for 3-aminotropones is described. Tropones and 3-aminotroponic building blocks, present in a number of active natural products, could be prepared by a two step synthetic pathway: a first step consisting in a [4+3] cycloaddition reaction between a conveniently substituted α,α′-dihaloketone and a furan derivative functionalized on C-2 by a protected amino group. The second step is based on a rearrangement of the cycloadduct, via the cleavage of the oxygen bridge, under basic conditions.