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1.
Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions 下载免费PDF全文
《化学:亚洲杂志》2018,13(18):2664-2670
A straightforward Lewis acid‐promoted protocol for 3,3′‐bisindolylmethanes (BIMs) synthesis by reductive alkylation of indoles at the C3 position with carboxylic acids in the presence of hydrosilane was developed for the first time. Instead of aldehydes, more readily available, stable, and easy‐to‐handle carboxylic acids have been employed as alternative alkylating agents. As an efficient organocatalyst, B(C6F5)3 enables the reductive alkylation of various substituted indole derivatives with carboxylic acids with up to 98 % yield at room temperature and under neat conditions. This metal‐free strategy offers an alternative approach for the direct functionalization of indoles to BIMs with carboxylic acids and such protocol allows selective reduction of carboxylic acid to aldehyde in combination with C−C bond formation. 相似文献
2.
Facile Installation of 2‐Reverse Prenyl Functionality into Indoles by a Tandem N‐Alkylation–Aza‐Cope Rearrangement Reaction and Its Application in Synthesis 下载免费PDF全文
Dr. Xiaobei Chen Huaqiang Fan Prof. Dr. Shilei Zhang Chenguang Yu Prof. Dr. Wei Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(2):716-723
An unprecedented tandem N‐alkylation–ionic aza‐Cope (or Claisen) rearrangement–hydrolysis reaction of readily available indolyl bromides with enamines is described. Due to the complicated nature of the two processes, an operationally simple N‐alkylation and subsequent microwave‐irradiated ionic aza‐Cope rearrangement–hydrolysis process has been uncovered. The tandem reaction serves as a powerful approach to the preparation of synthetically and biologically important, but challenging, 2‐reverse quaternary‐centered prenylated indoles with high efficiency. Notably, unusual nonaromatic 3‐methylene‐2,3‐dihydro‐1H‐indole architectures, instead of aromatic indoles, are produced. Furthermore, the aza‐Cope rearrangement reaction proceeds highly regioselectively to give the quaternary‐centered reverse prenyl functionality, which often produces a mixture of two regioisomers by reported methods. The synthetic value of the resulting nonaromatic 3‐methylene‐2,3‐dihydro‐1H‐indole architectures has been demonstrated as versatile building blocks in the efficient synthesis of structurally diverse 2‐reverse prenylated indoles, such as indolines, indole‐fused sultams and lactams, and the natural product bruceolline D. 相似文献
3.
Prof. Dr. A. Stephen K. Hashmi Weibo Yang Dr. Frank Rominger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(21):6576-6580
With the IPr ligand (IPr=1,3‐bis‐(2,6‐diisopropylphenyl)imidazol‐2‐ylidene) on gold(I) excellent yields in the benzanellation of 2‐substituted thiophenes, benzothiophenes, pyrroles, benzofurans, and indoles were achieved. The 1‐siloxybut‐3‐ynyl side chains, incorporated in the anellation, are easily accessible by the addition of a propargyl metal reagent to a formyl group and silylation of the alcohol. This conveniently allows an anellation at the position of the formyl group under mild conditions. All reactions involve a 2,3‐shift of the side chain in the anellation step and thus, provide an easy access to specific substitution patterns. Only in the case of 2‐substituted indoles with their highly nucleophilic 3‐position a direct hydroarylation without shift is observed. On the other hand, 3‐substituted indoles give the same products as 2‐substituted indoles. Then, a 3,2‐shift in the indole ring system has to be involved. 相似文献
4.
Jeffrey A Campbell Viola Bordunov Chris A Broka John Dankwardt Robert T Hendricks James M Kress Keith A.M Walker Jin-Hai Wang 《Tetrahedron letters》2004,45(19):3793-3796
The 3-arylmethylation of indoles using TMSOTf/Et3SiH with a wide variety of substituted benzaldehydes has been accomplished. Under these mild Lewis acid mediated reductive conditions, it was demonstrated that indoles bearing both 6-MeSO2 and 2-methyl substituents could be 3-arylmethylated in good to excellent yields to afford the corresponding 3-arylmethyl indoles, effective as selective COX-2 inhibitors. In addition, the viability of this method for the reductive alkylation of indoles by ketones was demonstrated and shown to be C-3 regioselective. For indoles bearing both a 6-MeSO2 and 2-cyano substituent where this indole reductive alkylation methodology was unsuccessful, an unprecedented Pd(0) mediated arylorganozinc coupling with the requisite substituted 3-methylcarbonatomethylindole proved successful in affording the desired 2-cyano-6-MeSO2-3-arylmethylindoles effective as selective COX-2 inhibitors. 相似文献
5.
Highly Enantioselective Synthesis of Indolines: Asymmetric Hydrogenation at Ambient Temperature and Pressure with Cationic Ruthenium Diamine Catalysts 下载免费PDF全文
Zhusheng Yang Fei Chen Yanmei He Prof. Nianfa Yang Prof. Dr. Qing‐Hua Fan 《Angewandte Chemie (International ed. in English)》2016,55(44):13863-13866
A highly enantioselective synthesis of indolines by asymmetric hydrogenation of 1H‐indoles and 3H‐indoles at ambient temperature and pressure, catalyzed by chiral phosphine‐free cationic ruthenium complexes, has been developed. Excellent enantio‐ and diastereoselectivities (up to >99 % ee, >20:1 d.r.) were obtained for a wide range of indole derivatives, including unprotected 2‐substituted and 2,3‐disubstituted 1H‐indoles, as well as 2‐alkyl‐ and 2‐aryl‐substituted 3H‐indoles. 相似文献
6.
An efficient Michael addition of indoles to electron‐deficient olefins under solvent‐ and catalyst‐free condition afforded biologically important 3‐substituted indole derivatives in good to excellent yields was reported. The acidic N? H proton of indole plays a key role in Michael addition of indoles to electron‐deficient olefins. This very simple procedure provides an efficient and clean process for the synthesis of indole derivatives. J. Heterocyclic Chem., (2011). 相似文献
7.
A two-step synthesis of 3-heteroaryl indoles has been developed. The first step of the sequence involves a Friedel-Crafts alkylation of indoles with 1,4-diaryl-2-buten-1,4-diones to give the corresponding indoles bearing a 1,4-dicarbonyl moiety. The reaction is catalyzed by InCl3 and takes place with good yields. Cyclization of the diones under different Paal-Knorr conditions allows to prepare indoles substituted at the C3 position with 3-furanyl, 3-pyrrolyl- and 3-thienyl moieties. 相似文献
8.
Iridium‐Catalyzed Enantioselective Indole Cyclization: Application to the Total Synthesis and Absolute Stereochemical Assignment of (−)‐Aspidophylline A 下载免费PDF全文
Dr. Shi‐Zhi Jiang Xue‐Yi Zeng Xiao Liang Ting Lei Dr. Kun Wei Prof. Yu‐Rong Yang 《Angewandte Chemie (International ed. in English)》2016,55(12):4044-4048
The first enantioselective total synthesis of (?)‐aspidophylline A, including assignment of its absolute configuration has been accomplished. A key element of the synthesis is a highly enantioselective indole allylic alkylation/iminium cyclization cascade which was developed by employing a combination of Lewis acid activation and an iridium/ligand catalyst. This strategy relies on the direct use of 2,3‐disubstituted indoles with secondary allylic alcohols appended at C2 and heteronucleophiles appended at C3, indoles which are easily prepared from simple starting materials under C?H activation conditions. 相似文献
9.
Sivakolundu Bhuvaneswari Dr. Masilamani Jeganmohan Dr. Chien‐Hong Cheng Prof. Dr. 《化学:亚洲杂志》2010,5(1):141-146
N‐Methyl indole reacts with but‐2‐yn‐1‐ol in the presence of PtCl2 in MeOH giving indole derivatives having a substituted 3‐oxobutyl group at the 3‐position in good yield. Under the reaction conditions, various substituted indoles and substituted propargyl alcohols are successfully involved in the reaction giving the corresponding addition products in good to moderate yields. The catalytic reaction can be further extended to N‐phenyl pyrrole. In the present multi‐step reaction, PtCl2 likely plays dual roles: as the catalyst for the rearrangement of propargyl alcohols to the corresponding alkenyl ketones and as the catalyst for the addition of indoles to the alkenyl ketones. Experimental evidence is provided to support the proposed mechanism. 相似文献
10.
James A. Rossi‐Ashton Aimee K. Clarke James R. Donald Chao Zheng Richard J. K. Taylor William P. Unsworth Shu‐Li You 《Angewandte Chemie (International ed. in English)》2020,59(19):7598-7604
The enantioselective intermolecular C2‐allylation of 3‐substituted indoles is reported for the first time. This directing group‐free approach relies on a chiral Ir‐(P, olefin) complex and Mg(ClO4)2 Lewis acid catalyst system to promote allylic substitution, providing the C2‐allylated products in typically high yields (40–99 %) and enantioselectivities (83–99 % ee) with excellent regiocontrol. Experimental studies and DFT calculations suggest that the reaction proceeds via direct C2‐allylation, rather than C3‐allylation followed by in situ migration. Steric congestion at the indole‐C3 position and improved π–π stacking interactions have been identified as major contributors to the C2‐selectivity. 相似文献
11.
Synthesis of Novel Chiral Phosphoric Acid‐Bearing Two Acidic Phenolic Hydroxyl Groups and its Catalytic Evaluation for Enantioselective Friedel‐Crafts Alkylation of Indoles and Enones 下载免费PDF全文
Xiong‐Li Liu Zhang‐Biao Yu Bo‐Wen Pan Lin Chen Ting‐Ting Feng Ying Zhou 《Journal of heterocyclic chemistry》2015,52(2):628-634
A novel chiral phosphoric acid catalyst bearing two acidic phenolic hydroxyl groups was synthesized. Its catalytic activity as a chiral Brøsted acid has been examined in the enantioselective Friedel‐Crafts alkylation of indoles and enones as a model reaction. In comparison with the other chiral phosphoric acid catalysts, the reaction catalyzed by the novel chiral catalyst afforded the desired 3‐substituted indoles in a higher enantioselectivity (up to 69% ee). 相似文献
12.
Giuseppe Cusati 《Tetrahedron letters》2008,49(16):2499-2502
A simple heterogeneously palladium-catalysed procedure for the selective C3-arylation of indoles is reported. Under relatively standard reaction conditions (Pd-catalyst, K2CO3, dioxane, reflux), using only 1 mol % [Pd(NH3)4]/NaY as the catalyst, indoles substituted or not at position 2 gave up to 92% conversion (i.e., 85% isolated yield) towards the expected C3-arylated indole. 相似文献
13.
Bartoli G Bartolacci M Bosco M Foglia G Giuliani A Marcantoni E Sambri L Torregiani E 《The Journal of organic chemistry》2003,68(11):4594-4597
Alkylation of indoles by means of the Michael addition has been the subject of a number of investigation. It is well established that regioselectivity in the additions of indoles to electron-deficient alkenes is strongly controlled by the reaction medium. In a continuation of the work on developing greener and cleaner technologies, the cerium(III) chloride heptahydrate and sodium iodide combination supported on silica gel catalyzes the alkylation of various indoles with alpha,beta-unsaturated ketones giving 3-(3-oxoalkyl)indole derivatives in good yields. The substitution on the indole nucleus occurred exclusively at the 3-position, and N-alkylation products have not been observed. 相似文献
14.
《Journal of heterocyclic chemistry》2017,54(2):1077-1083
The reaction of indoles with ninhydrin has been reported to provide only 1:1 condensation products (cf. A or 8 ) that show good antioxidant and anti‐inflammatory activity. In the present work, our synthetic challenge for the synthesis of innovative, highly substituted tetra‐indole indanes of type 1 via a 4:1 condensation reaction in acetic acid gave two unexpected new products, the diazatruxene derivatives 3 and 4 . The novel structures have been characterized by their analytical and spectral data including 1D‐ and 2D‐NMR. With 5‐chloroindole, only the known 1:1 reaction. 相似文献
15.
A library of 1,3-disubstituted indoles has been prepared via an iterative Mannich reaction sequence. The first Mannich reaction with secondary amines and formaldehyde preferentially yields 3-aminomethyl indoles, while the second Mannich reaction introduces an additional aminomethyl group at the N1-position of the indole ring. A library of 25 substituted indoles has thus been prepared in moderate to good yields with purity. 相似文献
16.
Hillier MC Marcoux JF Zhao D Grabowski EJ McKeown AE Tillyer RD 《The Journal of organic chemistry》2005,70(21):8385-8394
A general asymmetric synthesis of substituted cycloalkyl[b]indoles has been accomplished. The key features of this approach are (1) the utilization of a Japp-Klingemann condensation/Fischer cyclization to prepare cycloalkyl[b]indolones, (2) the asymmetric borane reduction of these heterocyclic ketones with (S)-OAB to obtain enantiomerically pure alcohols, and (3) the stereoselective S(N)2-displacement of these indole alcohol substrates with a carbon nucleophile under Mitsunobu conditions to set the C1 or C3 tertiary carbon stereocenter. The use of trimethylphosphine (PMe3) and bis(2,2,2-trichloroethyl) azodicarboxylate (TCEAD) was found to have an effect on the Mitsunobu dehydrative alkylation. 相似文献
17.
Efficient synthesis of furo[3,4-b]indoles starting from the corresponding indole is reported. The first route involves derivatization, protection, and deprotection steps, which stretch the syntheses. The second method provides a shorter and more efficient strategy to accessing the furoindole. The innovation starts with alkylation at C-2 of the indole presenting at the C-3 position a ketone-acetal, followed by the cycloaromatization catalyzed by polymeric ion-exchange resins. The second route represents a significant improvement over other methods previously described. 相似文献
18.
Kai Yang Yixian Lou Chenglan Wang Liang‐Wen Qi Tongchang Fang Feng Zhang Hetao Xu Lu Zhou Wangyang Li Guan Zhang Peiyuan Yu Qiuling Song 《Angewandte Chemie (International ed. in English)》2020,59(8):3294-3299
A new chiral Brønsted acid, generated in situ from a chiral phosphoric acid boron (CPAB) complex and water, was successfully applied to asymmetric indole reduction. This “designer acid catalyst”, which is more acidic than TsOH as suggested by DFT calculations, allows the unprecedented direct asymmetric reduction of C2‐aryl‐substituted N‐unprotected indoles and features good to excellent enantioselectivities with broad functional group tolerance. DFT calculations and mechanistic experiments indicates that this reaction undergoes C3‐protonation and hydride‐transfer processes. Besides, bulky C2‐alkyl‐substituted N‐unprotected indoles are also suitable for this system. 相似文献
19.
Can Liu Tao Miao Lei Zhang Prof. Pinhua Li Yicheng Zhang Prof. Lei Wang 《化学:亚洲杂志》2014,9(9):2584-2589
A novel and efficient palladium‐catalyzed C2 arylation of N‐substituted indoles with 1‐aryltriazenes for the synthesis of 2‐arylindoles was developed. In the presence of BF3 ? OEt2 and palladium(II) acetate (Pd(OAc)2), N‐substituted indoles reacted with 1‐aryltriazenes in N,N‐dimethylacetamide (DMAC) to afford the corresponding aryl–indole‐type products in good to excellent yields. 相似文献
20.
Rh-catalyzed C-H carbonylation of indoles under 1 atm of CO has been achieved. Various substituted indoles and indole with free N-H could be carboxylated with linear- and/or cyclic-alcohol to give the desired indole-3-carboxylates with up to 92% yield. A mechanism involving Rh(III) initiated C-H metallation is proposed. 相似文献