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120 results on '"Fan, Xue ‐ Sen"'

1. Solvent-free synthesis of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives under microwave irradiation

Author

Hu, Xue Yuan, Fan, Xue Sen, Zhang, Xin Ying, Qu, Gui Rong, and Li, Yan Zhen

Subjects
Radiation chemistry -- Research -- Chemical properties, Indium -- Chemical properties -- Research, Benzene -- Chemical properties -- Research, Chemistry, Chemical properties, Research
Abstract

Abstract: Several benzo-[b]-pyran derivatives were prepared via microwave irradiation under solvent-free conditions in the presence of In[Cl.sub.3] x 4[H.sub.2]O. The advantages of this method include simple operational process, environmental benignancy, [...]

Published
2006

8. Microwave-Promoted Metal-Free α-Alkylation of Ketones with Cycloalkanes through Cross-Coupling of C(sp3)−H Bonds.

Author

Wang, Qian ‐ Qian, Wang, Zhang ‐ Xin, Zhang, Xin ‐ Ying, and Fan, Xue ‐ SEN

Subjects
KETONES, CYCLOALKANES, COUPLING reactions (Chemistry)
Abstract

The microwave-promoted α-alkylation of ketones with cycloalkanes as alkylating agents under metal-free conditions is presented. The reaction mechanism involves the DTBP-initiated (DTBP=di- tert-butyl peroxide) microwave-assisted formation of the required cycloalkyl and α-ketone carbon radicals followed by a selective cross-coupling step. This is the first example in which simple ketones and 1,3-diketones have been efficiently alkylated with cycloalkanes under metal-free conditions through the cross-dehydrogenative coupling of C(sp3)−H bonds. Compared with previous methods, this alkylation protocol has advantages such as the use inexpensive and abundant substrates under metal-free conditions and its good atom-economy and sustainability. Moreover, the substituted ketones can be used as intermediates in the preparation of the synthetically and biologically valuable trisubstituted alkenes. [ABSTRACT FROM AUTHOR]

Published
2017
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13. Synthesis of 4-Oxo-but-2-enals through tBuONO and TEMPO-Promoted Cascade Reactions of Homoallylic Alcohols.

Author

He, Yan, Tian, Miao ‐ Miao, Zhang, Xin ‐ Ying, and Fan, Xue ‐ SEN

Subjects
STEREOSELECTIVE reactions, CARBON-carbon bonds, OXIDATION
Abstract

An efficient and stereoselective synthesis of ( E)-4-oxo-but-2-enals through tert-butyl nitrite ( tBuONO)- and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-promoted cascade reactions of homoallylic alcohols is presented. Mechanistically, the formation of the title compounds involves a cascade process including nitration of the carbon-carbon double bond, oxidation of the secondary alcohol unit, and Nef transformation of the in situ formed allylic nitro scaffold. In this process, tBuONO is an efficient nitration and oxidation reagent while TEMPO is believed to act as a mild oxidant and a novel reagent to promote the Nef reaction that is accomplished under mild and neutral conditions. As a further aspect, the ( E)-4-oxo-but-2-enals thus obtained were found to be suitable substrates to condense with hydrazine hydrate to give diversely substituted pyridazines with good efficiency. [ABSTRACT FROM AUTHOR]

Published
2016
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14. Bu4NI-Catalyzed and tBuOOH-Oxidized Esterification of Aldehydes with Alkyl Halides in Water.

Author

Wang, Qian ‐ Qian, Wang, Zhang ‐ Xin, Xu, Yuan ‐ Shuang, Zhang, Xin ‐ Ying, and Fan, Xue ‐ SEN

Subjects
ESTERIFICATION, ALDEHYDES, GLYCOSYLATION
Abstract

The importance of esters has stimulated significant efforts to develop efficient methods for their synthesis. In this study, an oxidative esterification of aldehydes with alkyl halides by using tert-butyl hydroperoxide as an oxidant, Bu4NI as catalyst, and water as solvent is presented. Notably, this novel esterification protocol is suitable for both aromatic and aliphatic aldehydes, primary and secondary alkyl halides to give ester products with broad structural diversity. Through an intramolecular version of this novel esterification process, an alternative synthetic approach toward the biologically interesting isobenzofuran-1(3 H)-one was also realized. Compared with literature procedures, the synthetic strategies developed herein showed advantages such as direct use of commercially available and economical starting materials, wide substrate scope, good tolerance of functional groups, sustainable oxidant, and no need of an inert atmosphere or dry solvents. [ABSTRACT FROM AUTHOR]

Published
2016
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19. Microwave‐Promoted Metal‐Free α‐Alkylation of Ketones with Cycloalkanes through Cross‐Coupling of C(sp3)−H Bonds

Author

Wang, Qian‐Qian, Wang, Zhang‐Xin, Zhang, Xin‐Ying, and Fan, Xue‐Sen

Abstract

The microwave‐promoted α‐alkylation of ketones with cycloalkanes as alkylating agents under metal‐free conditions is presented. The reaction mechanism involves the DTBP‐initiated (DTBP=di‐tert‐butyl peroxide) microwave‐assisted formation of the required cycloalkyl and α‐ketone carbon radicals followed by a selective cross‐coupling step. This is the first example in which simple ketones and 1,3‐diketones have been efficiently alkylated with cycloalkanes under metal‐free conditions through the cross‐dehydrogenative coupling of C(sp3)−H bonds. Compared with previous methods, this alkylation protocol has advantages such as the use inexpensive and abundant substrates under metal‐free conditions and its good atom‐economy and sustainability. Moreover, the substituted ketones can be used as intermediates in the preparation of the synthetically and biologically valuable trisubstituted alkenes. Rising to the challenge: The microwave‐promoted α‐alkylation of ketones with cycloalkanes as alkylating agents under metal‐free conditions is presented. This selective cross‐coupling of different carbon radicals is a challenge because of the inherent instability and reactivity of these intermediates. The cross‐coupling of C(sp3)−H bonds described herein provides a successful example of the realization of this difficult task.

Published
2017
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49. Synthesis of 2-Aminoquinoline-3-carboamides and Pyrimido[4,5-b]quinolin-4-ones through Copper-Catalyzed One-pot Multicomponent Reactions.

Author

Zhang, Xin ‐ Ying, Guo, Xiao ‐ Jie, and Fan, Xue ‐ Sen

Subjects
AROMATIC compound synthesis, COPPER catalysts, DEHYDROGENATION, HETEROCYCLIC compounds, FUNCTIONAL groups
Abstract

yrimido[4,5-b]quinolinones have attracted considerable interest from both chemical and medicinal scientists as these compounds display remarkable antimicrobial, anti-inflammatory, antitumor, antiallergy, analgesic, and antioxidant activities. The importance of pyrimido[4,5- b]quinolinones has stimulated enormous efforts to develop efficient methodologies for their synthesis. Herein, we disclose a novel synthetic protocol toward pyrimido[4,5- b]quinolin-4-ones through Cu(OAc)2-catalyzed one-pot four-component reactions of 2-bromobenzaldehydes, aqueous ammonia, cyanoacetamides and aldehydes. The synthetic procedure combines amination/condensation/ cyclization/dehydrogenation reactions in one pot, allowing synthesis of complex compounds in a simple and practical manner. Compared with literature procedures, the synthetic strategies developed herein showed advantages such as readily available and economically sustainable starting materials, structural diversity of products, good functional group tolerance, and a remarkably simple operation process. [ABSTRACT FROM AUTHOR]

Published
2015
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