环化反应合成2,3-二取代吲哚的研究进展

近年来,关于环化反应合成2,3-二取代吲哚的报道屡见不鲜.大多以苯肼类、苯胺类和硝基苯类等化合物为底物,在各种不同的金属及无金属催化作用下,与不同的底物反应,可以生成2,3-二取代吲哚及其衍生物.该类方法现已成为合成含氮五元杂环的一个重要手段,用来合成2,3-二取代吲哚及其衍生物.按反应底物类型的不同,对近年来环化反应合成2,3-二取代吲哚的研究进展进行了综述.     

三组分反应高效合成螺[环戊烷-1,3'-吲哚啉]衍生物（英文）

烷基异氰酸酯、丁炔二酸二酯(丙炔酸酯)和3-苯甲酰亚甲基-2-吲哚酮在甲苯中回流反应,高产率地生成螺[环戊烷-1,3'-吲哚啉]衍生物.然而,含有游离氨基的3-苯甲酰亚甲基-2-吲哚酮参加反应时,未取代的氨基可与另一分子丁炔二酸二酯及烷基异氰酸酯继续反应形成含有氨基取代的氮杂-1,3-二烯支链的螺[环戊烷-1,3'-吲哚啉]衍生物.另一方面,3-芳亚甲基吲哚-2-酮参与三组分反应时,仅有游离氨基参与反应,生成2-(2-氧吲哚-1-基)-3-[(烷基亚氨基)亚甲基]丁酸酯.发现两种游离氨基参与多组分反应时,分别形成了含有C2-取代的1-氮杂-1,3-丁二烯(C=C—C=NR)和C4-取代的1-氮杂-1,2-丁二烯(C—C=C=NR)结构单元的吲哚酮衍生物.     

葡萄糖酸溶液中三组分一锅法合成新型β-吲哚衍生物

在生物质葡萄糖酸水溶液中,醛、吲哚和2,2-亚戊基-1,3-二噁烷-4,6-二酮通过"一锅煮"三组分反应合成了13种新型β-吲哚衍生物,产率为66.4%~98.5%.该方法具有反应条件温和、底物普适性好、收率高及对环境友好等优点,为β-取代吲哚类化合物的合成提供了一种有效的新方法.     

基于未活化烯烃自由基加成/环化反应合成二氢吲哚类化合物的研究进展

二氢吲哚是一类具有广泛生物学特性的重要杂环,是许多天然产物和生物活性化合物的关键结构骨架.有效的二氢吲哚合成方法已成为广泛研究的主题.描述了利用未活化烯烃合成各种官能化二氢吲哚的最新研究,其涉及在氧化剂存在下的自由基加成/环化反应,这些反应通常用容易获得的氧化剂和不同的金属或非金属作为催化剂,在中性条件下进行反应.     

二氢吲哚-2,3-二酮衍生物抑菌活性研究进展

二氢吲哚-2,3-二酮是一种结构简单且应用广泛的药物小分子,其衍生物的合成、结构和药理活性等备受关注。已有报道表明二氢吲哚-2,3-二酮具有抗菌、抗衰老、降血脂、抗癫痫、抗病毒等多种生物活性。本文主要围绕抑菌生物活性,对国内外关于二氢吲哚-2,3-二酮类化合物的构效关系进行分析总结,为后期该类新型抗菌化合物的设计合成提供参考。     

Sc(OTf)_3/Bis(oxazoline)复合物催化的2-芳基-1,3-茚二酮与2-乙烯基吲哚的不对称Diels-Alder反应:高效构建四氢咔唑螺茚酮衍生物

报道了Sc(OTf)3/Bis(oxazoline)复合物催化的2-芳基-1,3-茚二酮与2-乙烯基吲哚的不对称Diels-Alder反应,简便、高效的构建了一系列手性四氢咔唑螺茚酮衍生物.通过考察不同的金属盐和手性配体、溶剂、温度等因素对反应的影响,获得了优良的收率(up to 92%yield)和优异的对映选择性(up to 94%ee).该反应条件温和,具有宽广的底物适用范围和较好的官能团兼容性.     

5-[(3-吲哚基)-甲基]-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物的高效合成

在分子碘作用下,以吲哚、醛和2,2-二甲基-1,3-二噁烷-4,6-二酮为原料,通过三组分缩合反应合成了10种5-[(3-吲哚基)-甲基]-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物。 当催化剂的用量为5%(摩尔分数)时,30 ℃反应60~90 min,收率为71.4%~97.3%。 此外,还探讨了分子碘的催化机理。     

硼酸催化三组分无溶剂“一锅法””合成5-[(3-吲哚基)-甲基]-2,2-亚丁基-1,3-二噁烷-4,6-二酮衍生物

在硼酸催化下,以吲哚、醛和2,2-亚丁基-1,3-二噁烷-4,6-二酮为原料,经三组分无溶剂条件合成了9种5-[(3-吲哚基)-甲基]-2,2-亚丁基-1,3-二噁烷-4,6-二酮衍生物.当催化剂的用量为5 mol%时,60℃反应30~90 min,收率为68.6%~91.3%.此外,还探讨了硼酸可能的催化机理.该方法具有反应条件温和,反应时间短且收率高的优点.硼酸催化剂对环境友好且可循环利用.     

手性磷酸催化的C（3）-取代吲哚和甲基乙烯基酮不对称串联反应

3位含有季碳手性中心的吲哚啉并环化合物是一类非常重要的化合物, 广泛存在于各种天然产物和具有生物活性的分子中. 化学家们发展了多种有效的途径来合成这类化合物. 其中以方便易得的吲哚衍生物为起始原料, 利用不对称去芳构化\环化串联的方法最为简单高效, 但多数工作都是从色胺或色醇衍生物出发, 合成二氢吡咯并吲哚啉或二氢呋喃并吲哚啉化合物. 因此, 发展其他类型的吲哚衍生物的不对称去芳构化\环化反应显得非常有必要. 作者课题组发展了手性磷酸催化的吲哚衍生物与甲基乙烯基酮的不对称Michael加成\环化串联反应. 以5 mol% (R)-SPINOL为骨架的手性磷酸(R)-4c为催化剂, 以中等到良好的收率和优秀的对映选择性构建了一系列手性吲哚[2,3-b]并氢化喹啉化合物, 而且该催化体系对于克级规模反应同样能够获得很好的结果.     

基于C—H键官能团化/环化串联策略构建吲哚酮分子骨架的研究进展

吲哚酮尤其是3,3-二取代吲哚酮化合物具有重要的生物活性作用,其合成方法的研究已成为有机化学的热点领域.近年来,以N-芳基丙烯酰胺为起始原料,通过与自由基的加成、环化反应构建吲哚酮骨架的研究受到广泛关注.综述了基于C—H键官能团化/环化串联策略构建3,3-二取代吲哚酮骨架分子的研究进展,并对反应的机理进行了概括总结.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.