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101.
Alexander S. Antonov Svetlana G. Kachalkina Alexander F. Pozharskii Gennady S. Borodkin Aleksander Filarowski 《Tetrahedron》2017,73(25):3452-3457
A novel approach to pyrrole ring closure in 2-trifluoroacetyl- and 2-ethoxycarbonyl-1,8-bis(dimethylamino)naphthalenes via treatment with 2-lithium-1,8-bis(dimethylamino)naphthalene producing the corresponding benzo[g]indole derivatives, was examined with different alkyl- and aryllithium compounds as well as with LDA. It was found that the highest yields of benzo[g]indoles (up to 70%) are obtained with aryllithium reagents when they contain NMe2 group in ortho-position to the carbanionic centre. In all other cases the formation of acyclic alcohol arising from ordinary intermolecular addition of the carbanion to the CO group strongly prevails. The dramatic facilitation of deprotonation of the N-Me group in substrate followed by pyrrolic cyclization in the case of 2-lithium-N,N-dimethylanilines was explained through a specific structure of the reaction transition state. 相似文献
102.
The Staudinger ketene-imine cycloaddition reactions of cyclobrassinin phytoalexin analogues 2-aryl-4,9-dihydro-1,3-thiazino[6,5-b]indoles with chloroacetyl chloride as a ketene source were investigated under different conditions. Both β-lactam ring formation and the N-chloroacetylation of the indole moiety took place. The indole N-chloroacetyl group can be easily removed by treatment in the presence of silica gel in methanol at reflux temperature. The selective β-lactam formation can be also achieved in certain cases under milder Staudinger conditions. The treatment of azeto[2,1-b]thiazino[6,5-b]indole-1-one derivatives with sodium ethoxide in ethanol provided the novel thiazepino[7,6-b]indole ring systems in a one-step ring transformation. The structures of the new ring systems were determined by means of IR and NMR spectroscopy. 相似文献
103.
Mostafa Kiamehr Batoul Alipour Leyla Mohammadkhani Behzad Jafari Peter Langer 《Tetrahedron》2017,73(21):3040-3047
Various novel polycyclic thiopyranoindol annulated [3,4-c]quinolone derivatives were synthesized via domino Knoevenagel-hetero-Diels–Alder reactions of indoline-2-thions and novel N-acrylated anthranilaldehydes in refluxing ethanol as a solvent in the presence of 20 mol% ZnBr2 as a Lewis acid catalyst. All reactions proceed with high yields with excellent regio- and stereoselectivity. 相似文献
104.
Sadia Naureen Fatima Ijaz Areesha Nazeer Faryal Chaudhry Munawar Ali Munawar Misbahul Ain Khan 《合成通讯》2017,47(16):1478-1484
An efficient, convenient green approach for the synthesis of indole-based 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles by multicomponent reaction of substituted 2-arylindole-3-carbaldehydes, benzil, substituted anilines, and ammonium acetate using catalytic amino acid (glycine) in ethanol is described. Several amino acids have also been evaluated as organic catalysts for these reactions. The structures of the compounds have been established on the basis of infrared, mass, and 1H NMR spectral data. The mild reaction conditions, inexpensive/economical reagents, and good yield show the usefulness of this approach. 相似文献
105.
Vikas Kumar Mehak Gupta Sumit G. Gandhi Sonali S. Bharate Ajay Kumar Ram A. Vishwakarma Sandip B. Bharate 《Tetrahedron letters》2017,58(42):3974-3978
Herein we report isolation of a new chromone alkaloid chrotacumine K (12) from fruits and a chromone glycoside schumaniofioside A (13) from leaves of Dysoxylum binectariferum Hook f. Schumaniofioside A is reported for the first time from Meliaceae family. Other known alkaloids isolated include rohitukine (1) and chrotacumine E (6). The structure of new alkaloid 12 was elucidated on the basis of extensive 1D and 2D NMR analysis, synthesis and chemical hydrolysis. Chemically, chrotacumine K (12) is a 3′-O-acetyl rohitukine which on chemical or enzymatic hydrolysis produces rohitukine. The new alkaloid 12 is also present in seeds and stem-barks of this plant. The glycoside schumaniofioside A (13) is present only in leaves, and in abundance (~1% w/w of dried leaves). The isolated compounds and extracts were evaluated for in vitro effect on the proinflammatory cytokines (TNF-α and IL-6) in human monocytic THP-1 cells. The alkaloid 12 displayed potent inhibition (57%) of TNF-α at 0.3 µM, and was non-toxic to THP-1 cells up to 40 µM, indicating its excellent therapeutic window. Furthermore, a nitrobenzoyl ester analog 15e showed better inhibition of IL-6 than parent natural product chrotacumine K. 相似文献
106.
Vinay K. Singh Rahul Dubey Abhishek Upadhyay Laxmi Kant Sharma Rana Krishna Pal Singh 《Tetrahedron letters》2017,58(45):4227-4231
An efficient and economical method was developed for synthesis of 3-substituted indole by using electrochemically induced condensation of various aldehyde, indole and malononitrile. 相似文献
107.
Taku Hirama Takayuki Umemura Noriyuki Kogure Mariko Kitajima Hiromitsu Takayama 《Tetrahedron letters》2017,58(3):223-226
A new procedure for the asymmetric total synthesis of lythraceous alkaloids with a 4-arylquinolizidine skeleton was developed, which involved an organocatalyzed asymmetric intramolecular aza-Michael addition. 相似文献
108.
Qing-Dong Wang Jin-Ming Yang Dong Fang Jiangmeng Ren Bu-Bing Zeng 《Tetrahedron letters》2017,58(30):2877-2880
An efficient iodine-catalyzed chemoselective 3-formylation of free (N–H) and N-substituted indoles was achieved by using hexamethylenetetramine (HMTA) in the presence of activated carbon under air atmosphere. This new method could provide 3-formylindoles in moderate to excellent yields with fairly short reaction times. Moreover, this catalytic formylation of indoles procedure can be applied to gram-scale synthesis. 相似文献
109.
铈修饰的硼铝酸铜催化邻乙基苯胺脱氢环化制备吲哚的催化性能 总被引:1,自引:1,他引:0
硼铝酸铜催化剂(CuAB)在吲哚制备过程中存在易积碳和还原的缺点,通过添加铈助剂来改善该催化剂的抗还原性能.通过BET、XRD、H2-TPR、XPS表征表明,铈助剂的添加对催化剂的主体晶相没有改变,但显著增强了复合氧化物的抗还原能力,降低了催化剂的失活速度.采用2%Ce修饰量、空速为0.75 h-1、水油比(摩尔比)为6∶1的条件下,较未添加助剂改性的催化剂转化率提高11.81%,选择性提高6.47%. 相似文献
110.
Kurosh Rad-Moghadam Masoumeh Sharifi-Kiasaraie Homayun Taheri-Amlashi 《Tetrahedron》2010,66(13):2316-241
Three ionic liquids, [BMIM][BF4] doped with 60 mol % of LiCl ([BMIM][BF4]-LiCl), N,N,N,N-tetramethylguanidinium trifluoroacetate (TMGT), and N,N,N,N-tetramethylguanidinium triflate (TMGTf) were found useful as catalyst solvents for controlled 3-indolylation of isatins. Our investigation revealed that the reaction between isatin and indoles in [BMIM][BF4]-LiCl or TMGTf media stops at the step of addition of the two components providing 3-indolyl-3-hydroxyindolin-2-ones while the ionic liquid TMGT runs the reaction further through accompanying Friedel-Crafts substitution to afford symmetrical 3,3-di(indol-3-yl)indolin-2-ones. To take advantage of the difference between the effects of these ionic liquids on the reaction progress, we planned a two-step protocol for the efficient synthesis of unsymmetrical 3,3-di(indol-3-yl)indolin-2-ones. 相似文献