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991.
Chao Wang Changpeng Chen Jingyu Zhang Jian Han Qian Wang Kun Guo Pei Liu Mingyu Guan Yingming Yao Yingsheng Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(37):10042-10046
An easily synthesized and accessible N,O‐bidentate auxiliary has been developed for selective C H activation under palladium catalysis. The novel auxiliary showed its first powerful application in C H functionalization of remote positions. Both C(sp2) H and C(sp3) H bonds at δ‐ and ε‐positions were effectively activated, thus giving tetrahydroquinolines, benzomorpholines, pyrrolidines, and indolines in moderate to excellent yields by palladium‐catalyzed intramolecular C H amination. 相似文献
992.
A silver-catalyzed reaction of 2-alkynylbenzaldoxime with arylsulfonyl chloride proceeds smoothly at room temperature to afford 4-tosyloxyisoquinolines in moderate to good yields. Additionally, the resulting 4-tosyloxyisoquinolines could be further elaborated through palladium-catalyzed coupling reactions leading to diverse isoquinolines. 相似文献
993.
Ling-Fang Lei Min-Feng Chen Tao Wang Xi-Xin He Bing-Xin Liu Yun Deng Xiao-Jie Chen Yu-Ting Li Shan-Yue Guan Jun-Hua Yao Wei Li Wen-Cai Ye Dong-Mei Zhang Cui-Xian Zhang 《Tetrahedron》2014
One novel nine-membered macrocyclic polysulfur cembranoid lactone, sinulariaoid A (1); three new multioxygenated cembranoids, sinulariaoid B (2), sinulariaoid C (3), sinulariaoid D (4); and four known cembranoids, capilloloid (5), dihydrosinularin (6), sinularin (7), and dihydrosinuflexolide (8) were isolated from the soft coral Sinularia sp. collected off of Sanya Bay in the South China Sea. Their stereochemical structures were determined on the basis of extensive spectroscopic methods, including single crystal X-ray diffraction analysis. Sinulariaoid A (1) is the first reported nine-membered macrocyclic polysulfur cembranoid from soft coral. The cytotoxic activities of compounds 1–8 were determined in four human cancer cell lines (HepG2, HepG2/ADM, MCF-7, and MCF-7/ADM). Of these, sinulariaoid A (1) exhibited the most potent anticancer activity in vitro, and its cytotoxicity in HepG2/ADM was more potent than in the other three cell lines. Furthermore, it was found that sinulariaoid A (1) induced apoptosis, and its selective toxicity toward HepG2/ADM cells was not related to P-glycoproteins. 相似文献
994.
An efficient and practical method for the synthesis of cyano, sulfonyl and phosphoryl substituted naphthalene derivatives via the rearrangement aromatization of benzo[c]oxepine has been developed. The system holds the advantages of metal catalysts free, and mild reaction conditions. 相似文献
995.
The NMR spin–spin scalar coupling constants (JHH's) of closely contacting, but non-bonded hydrogen atoms in a series of highly strained molecules (including a new in,in-cyclophane made specifically for this study) have been examined both experimentally and computationally. The experimental JHH's are invariably quite small (0.1–0.6 Hz), but common DFT methods with modest basis sets nearly always overestimate these values, by factors of 10–30, and even with quite large basis sets (up to cc-pVQZ) the JHH's of two of the molecules are overestimated by a factor of 10 or more. Possible reasons for these discrepancies are discussed. 相似文献
996.
Deepak Kumar Barange Veerababurao KavalaChun-Wei Kuo Cheng-Chuan WangR.R. Rajawinslin Janreddy DonalaChing-Fa Yao 《Tetrahedron》2014
An efficient regioselective synthesis of 4-iodo-2,3-disubstituted-2H-thieno[3,2-e][1,2]thiazine-1,1-dioxide derivatives via iodocyclization approach using iodine under mild reaction condition described herein. This coupling–iodocyclization strategy tolerated a variety of functional groups such as alkyl, cycloalkyl, phenyl producing the six-membered heterocyclic ring selectively. The resulting 4-iodo-2,3-disubstituted-2H-thieno[3,2-e][1,2]thiazine-1,1-dioxide was coupled with a variety of boronic acids (Suzuki coupling) and activated alkenes (Heck coupling). The iodo group was utilized for Sonogashira coupling followed by efficient transformation to azido precursor, which was used for the synthesis of various thieno-sultam linked with triazole. 相似文献
997.
Li-Xia Wang Ben-Quan Hu Jun-Feng Xiang Jie Cui Xiang Hao Tong-Ling Liang Ya-Lin Tang 《Tetrahedron》2014
Hydrogen bonding interaction as one type of non-covalent force has proven itself to be highly efficient for constructing structurally unique artificial secondary structures. Here, the structure of Naryl-substituted anthranilamide in solution is demonstrated by various NMR technique, the intramolecular hydrogen bonds between amide attached to arylamine of the same ring is proposed, which is supported by its crystal structure in the solid phase. The substituent on the nitrogen atom of arylamine plays an important role in forming the presence of intramolecular hydrogen bonds. The chemical shift of the Naryl-H downfield changes obviously, due to the formation of intramolecular hydrogen bonds and the deshielding effect of oxygen, and the neighboring C–H is activated and shows downfield protonic signal too. The presence of intramolecular hydrogen bonds probably provides the explanation for the transformation from Naryl-substituted anthranilamide to imine, which could be converted into 2-aryl quinazolinone finally. 相似文献
998.
A silver(I)-catalyzed reaction of 2-alkynylaryl aldimine with trimethyl(trifluoromethyl)silane is reported. This reaction proceeds efficiently under extremely mild conditions to generate 1-(trifluoromethyl)-1,2-dihydroisoquinolines in good yields. A three-component reaction of 2-alkynylbenzaldehyde, amine, with trimethyl(trifluoromethyl)silane is presented as well. 相似文献
999.
1000.
Hucheng Zhu Lijun Huan Chunmei Chen Jing Yang Jiangbo He Yong Chen Guangmin Yao Zengwei Luo Yongbo Xue Yonghui Zhang 《Tetrahedron letters》2014
A pair of unprecedented enantiomers (1a/1b) of cyclohexylethanoid bearing an unusual trioxabicyclo[4.2.1]nonane ring, along with two known structurally related cyclohexylethanoids, (+)-rengyolone (2) and cleroindicin E (3), were isolated from the aerial parts of Clerodendrum bungei. The structures and absolute configurations of the enantiomers were determined by comprehensive spectroscopic analysis, single-crystal X-ray diffraction, and quantum mechanical calculation of the electronic circular dichroic (ECD) spectra. The postulated biogenetic pathway of 1a/1b was also discussed. 相似文献