Fischer吲哚合成法的研究进展

吲哚及其衍生物具有某些生物活性, 其合成方法很多. 其中Fischer吲哚合成是最便捷和经济的合成方法, 应用最多. 对此法近十年来的合成工艺进行了综述和评价.     

Fischer吲哚合成法合成舒马普坦

舒马普坦是一种起效快耐受性好的治疗偏头痛的标准药物,目前市场前景看好。本研究用Fischer吲哚合成法,以4-肼基-N-甲基苯甲烷磺酰胺盐酸盐（Ⅰ）和4．N,N-二甲胺基丁醛缩二甲醇（Ⅱ）为原料,在甲醇／乙酸溶剂中先缩合形成腙不经分离在浓盐酸催化下一步直接得到了舒马普坦。实验表明,该方法操作简单且重复性好,粗产品通过高效液相色谱测定其含量为56％;产品经柱色谱纯化后产率为37％。产物结构经红外光谱、氢核磁共振谱分析得以确认。     

An Isomeric Swapping of a Phenylhydrazone Derivative Discovered by Structural Study Revealing a Branched Pathway of Fischer Indole Synthesis

In an attempt to synthesize an indole derivative,methyl 5-nitro-1H-indole-2-carb-oxylate,an isomeric change of methyl 2-[2-(4-nitrophenyl) hydrazono] propanoate from E to Z geometry was observed.The two isomers were determined by single-crystal X-ray diffraction analysis.The Z isomer is stabilized in a six-membered ring conformation constructed by an intramolecular hydrogen bond.This isomeric change added a branched pathway in the mechanism of Fischer indole synthesis.     

Fischer indole synthesis of the indoloquinoline alkaloid: cryptosanguinolentine

A new synthesis of an indoloquinoline alkaloid, isolated from Cryptolepis sanguinolenta, is described using a Fischer indole cyclization. 4-Hydroxy-1-methyl-1H-quinolin-2-one reacted directly with phenylhydrazine hydrochloride to give the indoloquinoline, which was reacted with POCl₃ and then the resultant halide hydrogenolysed to give cryptosanguinolentine.     

新型N-甲基吲哚类衍生物的设计、合成及抗肿瘤活性研究

本文以吲哚骨架为起点,设计合成了5个含吲哚骨架的新型有机小分子(4a-4e),通过NMR,IR和MS对目标化合物进行了结构表征.采用MTS法测试了目标化合物对SMMC-7721,Hela,MCF-7和HepG2癌细胞的体外抗肿瘤活性.结果表明,部分化合物选择性地作用于一种细胞,显示出较强的抑制肿瘤细胞增殖的活性,值得进一步研究.     

Synthesis of Fischer indole derivatives using carboxyl-functionalized ionic liquid as an efficient and recyclable catalyst

Fischer indole cyclization of phenylhydrazine and various ketones using carboxyl-functionalized ionic liquid, 1-carboxymethyl-3-methylimidazolium tetrafluoroborate (abbreviated as [cmmim][BF4]) as catalyst was successfully performed. The yields of thetarget compounds were 80-92%, the purities were 96-98%. The catalyst could be rocovered and reused for at least six times without significant loss in activity.     

Novel biodegradable protonic ionic liquid for the Fischer indole synthesis reaction

Novel eco-friendly tetramethylguanidinium propanesulfonic acid trifluoromethylacetate ([TMGHPS][TFA]) ionic liquid was developed as catalyst and medium for the Fischer indole synthesis of a wide variety of hydrazines and ketones. The indole products were isolated in high yields and with minimal amounts of organic solvent. This reaction showed that [TMGHPS][TFA] can be regenerated and reused with reproducible yields without eroding the integrity of the ionic liquid.     

One-pot synthesis of 2-substituted thieno[3,2-b]indoles from 3-aminothiophene-2-carboxylates through in situ generated 3-aminothiophenes

A convenient protocol for one-pot synthesis of thieno[3,2-b]indoles, bearing aromatic, thien-2-yl or styryl fragments at C-2 position, from easily accessible 5-substituted 3-aminothiophene-2-carboxylates using the Fischer indolization reaction, was developed during this study. Two main steps of this approach are the saponification of the starting 3-aminoesters with sodium hydroxide and next treatment of the crude 3-aminoacids sodium salts with arylhydrazines in glacial acetic acid solution. The latter step includes in situ decarboxylation of the freed 3-aminothiophene-2-caboxylic acids to the 3-aminothiophenes and their acid promoted reaction with arylhydrazines to initially form arylhydrazones of 5-substituted thiophene-3(2H)-ones, which smoothly cause indolization to afford the desired thieno[3,2-b]indoles.     

6-甲氧基-1,2,3,9-四氢-4H-咔唑-4-酮肟的一锅合成

报道了6-甲氧幕-1,2,3,9-四氢-4H-咔唑-4-酮肟(3b)的一锅合成法,将Fischer吲哚合成与肟化两步反应并为一步,可简化操作,提高收率.反应可以在弱碱性且温度温和的条件下一锅合成,是由于肟化使Fischer吲哚环合变得容易,羰基与肟基在互变异构方向上的差别是影响环合反应的关键因素.     

p-TsOH promoted Fischer indole synthesis of multi-substituted 2-trifluoromethyl indole derivatives

A p-TsOH promoted one-pot synthesis of multi-substituted 2-trifluoromethyl indole derivatives, for instance, 2-trifluoromethyl-3-phenylindoles, 2-trifluoromethyl-indole-3-propanoates, and 2-trifluoromethyl-indole-3-butanoates from reactions of 1,1,1-trifluoro-3-phenylacetone and simply prepared ω-trifluoromethyl substituted δ and ?-ketoesters with arylhydrazines via Fischer indole synthesis has been developed.     

Novel approach to arylhydrazones, the precursor for Fischer indole synthesis, via diazo esters derived from α-amino acid esters

A novel method for synthesizing arylhydrazones, the precursor for Fischer indole synthesis, using aryllithium reagents and α-diazo esters that are easily obtained from α-amino acid esters, is described.     

Novel method for synthesis of aryl hydrazones from α-diazo esters: scope and limitations of nucleophiles

Aryl hydrazones, the precursor of Fischer indole synthesis, were easily obtained by nucleophilic addition of aryllithium reagents to diazo esters. The aryl hydrazones were converted into indoles in good yields by heating with thionyl chloride in alcohol. Grignard reagent was also a good nucleophile, whereas organozinc reagent did not react with diazo esters. Aryllithium reagents were prepared by reacting aryl bromides having various substitutions at 2-, 3-, 4-, or multi positions with n-BuLi. The addition of nucleophiles derived from bromopyridines to diazo esters also gave hydrazones.     

Exploration of the interrupted Fischer indolization reaction

A convergent method to access the fused indoline ring system present in a multitude of bioactive molecules has been developed. The strategy involves the condensation of hydrazines with latent aldehydes to ultimately deliver indoline-containing products by way of an interrupted Fischer indolization sequence. The method is convergent, mild, operationally simple, broad in scope, and can be used to access enantioenriched products. In addition, our approach is amenable to the synthesis of furoindoline and pyrrolidinoindoline natural products as demonstrated by the concise formal total syntheses of physovenine and debromoflustramine B. The strategy will likely enable the synthesis of more complex targets such as the communesin alkaloids.     

Bidirectional synthesis of montamine analogs

Reported herein is a bidirectional synthesis of symmetric N,N′-diacyl hydrazide compounds closely resembling the alkaloid natural product montamine. In the process, di-tert-butyl hydrazine-1,2-dicarboxylate was smoothly dialkylated with alkyl halides, then Boc deprotected and acylated with an acetate-protected acid chloride derived from ferulic acid. After acetate removal, simple montamine analogs were obtained in excellent overall yields. Fischer indole synthesis with 4-methoxyphenylhydrazine hydrochloride and dihydrofuran provided 5-methoxytryptophol, which was then elaborated to the 1,2-bis(5-methoxyindol-3-yl)hydrazide structure bearing the substitution pattern found in montamine.     

Synthesis of 9-Bromo-2-fluoro-6,7-dihydro-5H-benzocycloheptene-8-carboxaldehyde

Cinnamaldehye is an antioxidant shown to induce apoptotic cell death in a number of human cancer cells. This article reports a synthesis of 9-bromo, 2-fluoro substituted, and Z-ring locked (by a trimethylene bridge at C-8 and C-11) crystalline fluorine-substituted derivative of cinnamaldehyde. The synthon, 8-fluoro-1-benzosuberone was treated with PBr₃, dimethylformamide (DMF), and CHCl₃ as a solvent to obtain 9-bromo-2-fluoro-6,7-dihydro-5H-benzocycloheptene-8-carboxaldehyde. The one-step trifunctionalization process converts a bicyclic ring–fused ketone into a β-bromo-α,β-unsaturated aldehyde in a chemoselective and regioselective manner. The process also creates a new carbon–carbon bond between C-8 and C-12. The structure of the previously unreported product has been obtained by x-ray crystallographic analysis. It has been characterized spectroscopically by infrared (IR), ¹H NMR, ¹³C NMR, gas chromatography–mass spectrometry (GC-MS), and elemental analysis. It is a structural element found in sterically hindered retinoids and is a useful advanced intermediate in the total synthesis of these naturally occuring bioactive polyenes.     

Convenient and Efficient Synthesis of 1-Oxo-1,2,3,4-tetrahydrocarbazoles via Fischer Indole Synthesis

A convenient synthesis of 1-oxo-1,2,3,4-tetra-hydrocarbazoles has been developed by reaction of 2-aminocyclohexanone hydrochlorides with various phenylhydrazine hydrochlorides via Fischer indole synthesis under mild conditions. The method is more satisfactory in terms of the easy availability of starting materials and the simple one-pot operation.     

17β-雄甾醇-[3,2-b]-吲哚的合成

以表雄酮为原料,经羟基氧化、羰基保护、还原、Fischer吲哚环化等反应合成了17-β-醇-雄甾-[3,2-b]-吲哚(5),总收率43.2%,其结构经1H NMR,IR和MS确证。生物活性初步测试结果表明:与雄诺龙相比,5对淡色库蚊的杀虫活性显著提高,在浓度为400 mg·L-1时,杀虫率为41.5%。     

Efficient and Straightforward Synthesis of Tetrahydrocarbazoles and 2,3-Dimethyl Indoles Catalyzed by CAN

A simple protocol was established to synthesize 2,3-dialkyl indoles and various tetrahydrocarbazoles via Fischer indole synthesis. This method uses ceric ammonium nitrate as a catalyst for the Fischer indole synthesis with substituted phenyl hydrazine hydrochlorides and 2-butanone, phenyl propanal, and cyclohexanone. This process is a practical synthetic method for the preparation of various 2,3-disubstituted alkyl indoles and tetrahydrocarbazoles.     

Syntheses of 4-, 5-, 6-, and 7-substituted tryptamine derivatives and the use of a bromine atom as a protecting group

Orthogonal syntheses of 4-, 5-, 6-, and 7-chloro substituted tryptamine derivatives were performed under the Grandberg–Zuyanova-modified Fisher indole-synthesis conditions. In the 4- and 6-substituted tryptamine cases, a bromine atom was utilized as an easily cleavable protecting group, which allowed complete regiocontrol. In addition, a chlorine substituent was preserved in the debromination step and could be utilized as a synthetic handle for late-stage diversification under modern Pd(0) catalysis conditions.     

Facile zeolite induced Fischer-indole synthesis: a new approach to bioactive natural product rutaecarpine

Starting from glutaric anhydride (5) we have demonstrated an elegant six-step practical synthesis of bioactive natural product rutaecarpine (1a) via o-amidoglutaranilic acid formation, esterification, chemoselective ester reduction, intramolecular dehydrative cyclizations, hydrazone formation and zeolite induced Fischer-indole synthesis with 53% overall yield. The conditions employed in the present synthesis are mild, efficient and general.