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1.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(7):1907-1910
A redox‐neutral, light‐mediated functionalization of unactivated C(sp3)−H bonds via iminyl radicals is presented here. A 1,5‐H transfer followed by the functionalization of a C(sp2)−H bond takes place in aqueous media producing a variety of elaborated fused ketones. Mechanistic investigations have revealed 1,5‐H transfer as the reversible, rate‐determining step in this transformation. Divergent scaffolds are also accessible via C(sp3)−N bond formation upon a careful choice of the reaction additives. 相似文献
2.
Yuhsuke Akagi 《Tetrahedron letters》2010,51(9):1338-387
Dimethyljadomycin A was synthesized as the first example for the construction of 8H-benzo[b]oxazolo[3,2-f]phenanthridine skeleton. 相似文献
3.
Miada F. Abdelwahab Tibor Kurtán Attila Mándi Werner E.G. Müller Mostafa A. Fouad Mohamed S. Kamel Zhen Liu Weaam Ebrahim Georgios Daletos Peter Proksch 《Tetrahedron letters》2018,59(27):2647-2652
Two new cryptic 3,4-dihydronaphthalen-(2H)-1-one (1-tetralone) derivatives, aspvanicin A (1) and its epimer aspvanicin B (2), as well as several known cryptic metabolites (3–8), were obtained from the ethyl acetate extract of the co-culture of the endophytic fungus Aspergillus versicolor KU258497 with the bacterium Bacillus subtilis 168 trpC2 on solid rice medium. When A. versicolor was cultured axenically in liquid Wickerham medium supplemented with 3.5% DMSO, an additional three known secondary metabolites (9–11) were isolated that were lacking when the fungus was fermented on rice medium. The structures of the new compounds were elucidated using one- and two-dimensional NMR spectroscopy as well as HRESIMS. The relative and absolute configurations of 1 and 2 were determined by the combination of NMR and electronic circular dichroism (ECD) analysis aided by DFT conformational analysis and TDDFT-ECD calculations. The ECD calculations revealed that although the sign of the blue-shifted overlapping n-π1 ECD transition follows the helicity rule of cyclic aryl ketones, the calculation of low-energy conformers and ECD spectra was necessary to determine the stereochemistry. All metabolites were assessed for their antibacterial and cytotoxic activities; one of the new diastereomers, compound 2, showed moderate cytotoxic activity against the mouse lymphoma cell line L5178Y. 相似文献
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5.
Qing Liu Ping Zhao Xing‐Cong Li Melissa R. Jacob Chong‐Ren Yang Ying‐Jun Zhang 《Helvetica chimica acta》2010,93(2):265-271
Three new α‐tetralone galloylglucosides, 1 – 3 , were isolated from the fresh pericarps of Juglans sigillata (Juglandaceae), together with six known compounds. The structures of the new compounds were determined as 1,2,3,4‐tetrahydro‐7‐hydroxy‐4‐oxonaphthalen‐1‐yl 6‐O‐[(3,4,5‐trihydroxyphenyl)carbonyl]‐β‐D ‐glucopyranoside ( 1 ), (1S)‐1,2,3,4‐tetrahydro‐8‐hydroxy‐4‐oxonaphthalen‐1‐yl 6‐O‐[(3,4,5‐trihydroxyphenyl)carbonyl]‐β‐D ‐glucopyranoside ( 2 ), and 1,2,3,4‐tetrahydro‐7,8‐dihydroxy‐4‐oxonaphthalen‐1‐yl 6‐O‐[(3,4,5‐trihydroxyphenyl)carbonyl]‐β‐D ‐glucopyranoside ( 3 ), respectively, on the basis of detailed spectroscopic analyses, and acidic and enzymatic hydrolysis. The antimicrobial activities of the isolated compounds 2, 4 , and 7 – 9 were evaluated. 相似文献
6.
Aly H. Atta 《中国化学会会志》2006,53(3):663-667
Some spiro indolone derivatives 5a,b and 6 were synthesized through one‐pot synthesis via the ternary condensation of 1H‐indole‐2,3‐dione 1 , 3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one 2 and active methylenes, namely malononitrile, ethyl cyanoacetate 4a,b and pyrazolone 2 , respectively. The same derivatives can be obtained via other methods, through reactions of 3‐[3‐methyl‐5‐oxo‐1‐phenyl‐1,5‐dihydro‐pyrazol‐(4Z)‐ylidene]‐1,3‐dihydro‐indol‐2‐one 3 with the corresponding active methylenes. Reaction of 3 with amines and with ethyl vinyl ether was studied. 相似文献
7.
We have developed an efficient synthesis of novel racemic spiropyrrolidine-tetralones via an unexpected ring-contraction reaction of a 4-disubstituted piperidine to 3-disubstituted pyrrolidine. We suggest that intramolecular quaternization of the piperidine nitrogen of compound 7 occurs to form a bridged bicyclic quaternary ammonium salt intermediate 10. The ring opening of 10 with cyanide resulted in pyrrolidine 9. The synthesis of racemic spiropyrrolidine-tetralone 15 is described as well as the related spiropiperidine-indanone, 1b. 相似文献
8.
A new and efficient method of double bond functionalization of eudesmanolide was carried out by rearrangement of epoxide with methoxide. which is important to synthesis of bioactive natural products containing denebutenolid (1) and endocyclic α, β -unsaturated butenolide (2). 相似文献
9.
Ramendra Pratap 《Tetrahedron letters》2007,48(10):1715-1719
An innovative and efficient route to the synthesis of 9,10-dihydro-3-formylphenanthrenes 7 has been delineated through the ring transformation of 2-oxo-4-sec-amino-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles 4 with methyl glyoxaldimethylacetal 5 to masked 3-dimethoxymethyl-1-sec-amino-9,10-dihydrophenanthrene-3-carbonitriles 6 followed by deacetalation with Amberlyst 15 in excellent yields. 相似文献
10.
Cong‐Ying Li Hong‐Jian Du Xue‐Hui Su Yu‐Jiao Zhong Zhi‐Peng Yuan Yan‐Fang Li Bing Liang 《Helvetica chimica acta》2013,96(6):1031-1035
Two novel tetralone dimers, with an O‐bridge, named juglanones A and B ( 1 and 2 , resp.), were isolated from the AcOEt extract of walnut pericarps. These compounds are the first examples of O‐bridged dimeric tetralones. Their structures were determined by spectroscopic methods, including HR‐TOF‐MS, and 1D‐ and 2D‐NMR. Biological evaluation of these two isolates against a number of human cancer cell lines is also described. 相似文献