نتایج جستجو برای: multisubstituted pyrroles

تعداد نتایج: 2001  

Journal: :Chemical communications 2015
Yin Zheng Youming Wang Zhenghong Zhou

We have developed an organocatalyzed three-component reaction of 1,2-diones, aldehydes and arylamines, which provides an efficient approach to access polysubstituted pyrroles. In the catalysis of 4-methylbenzenesulfonic acid monohydrate, the reactions of a wide range of 1,2-diones, arylamines and aldehydes took place smoothly to generate the corresponding polysubstituted pyrroles in acceptable ...

Journal: :Organic letters 2015
Lei Zhu Yinghua Yu Zhifeng Mao Xueliang Huang

An effective gold-catalyzed intermolecular nitrene transfer by the reaction of 2H-azirines and ynamides is reported, which provides highly substituted pyrroles in a straightforward manner. This transformation proceeds under mild conditions and gives the polysubstituted pyrroles in good-to-excellent yields. Preliminary results indicate that a nongold carbenoid pathway is preferred for current py...

Journal: :Molecules 2007
Shive Murat Singh Chauhan Bhaskar Garg Tanuja Bisht

A facile and efficient protocol is reported for the synthesis of calix[4]pyrroles and N-confused calix[4]pyrroles in moderate to excellent yields by reaction of dialkyl or cycloalkyl ketones with pyrrole catalyzed by reusable Amberlyst(TM)-15 under eco-friendly conditions.

Journal: :The Journal of organic chemistry 2016
Tengfei Li Hao Yan Xincheng Li Chunxiang Wang Boshun Wan

A ruthenium-catalyzed intermolecular [3 + 2] cycloaddition of 2H-azirines and activated alkynes is reported, which provides polysubstituted pyrroles in moderate to good yields. This approach features a C-N bond cleavage of 2H-azirines by a ruthenium catalyst. The results of this study would provide a complementary method to synthesize polysubstituted pyrroles from the known 2H-azirine approache...

Journal: :Chemical communications 2013
Jie Ke Chuan He Huiying Liu Mengjun Li Aiwen Lei

A novel silver-mediated highly selective synthesis of polysubstituted pyrroles by the C-H/C-H oxidative cross-coupling/cyclization of terminal alkynes with β-enamino esters has been developed. This protocol represents a simple, efficient and selective way to construct polysubstituted pyrroles in good yields from basic chemical materials.

Journal: :Chemical communications 2011
Sami Lakhdar Herbert Mayr

Electrophilic substitution of pyrroles by α,β-unsaturated iminium ions is slow in acetonitrile when only weakly basic counterions are present. When the reactions are carried out in the presence of KCF(3)CO(2), fast deprotonation of the intermediate σ-adducts occurs, and the rate constant for the rate-determining CC bond-forming step can be predicted from the electrophilicity parameter E of the ...

Journal: :Chemical communications 2011
Simbarashe Ngwerume Jason E Camp

O-Vinyl oximes were synthesised from the reaction of oximes with activated alkynes and subsequently rearranged using gold catalysis to afford highly substituted pyrroles in an efficient and regiocontrolled process. Additionally, pyrroles were formed directly from oximes and activated alkynes in a multifaceted catalysis process.

Journal: :Journal of the American Chemical Society 2008
Ryoichi Kuwano Manabu Kashiwabara Masato Ohsumi Hiroki Kusano

Catalytic asymmetric hydrogenation of N-Boc-protected pyrroles proceeded with high enantioselectivity by using a ruthenium catalyst modified with a trans-chelating chiral bisphosphine PhTRAP. The ruthenium catalyst prepared from Ru(eta3-methallyl)2(cod) and (S,S)-(R,R)-PhTRAP in the presence of triethylamine was the most enantioselective for the asymmetric hydrogenation of methyl pyrrole-2-carb...

Journal: :Molecules 2017
Xueming Zhang Xianxiu Xu Dawei Zhang

A facile access to polysubstituted 3-(isoxazol-5-yl)pyrroles was developed through [3+2] cycloaddition of tosylmethyl isocyanide (TosMIC) and styrylisoxazoles. In the presence of KOH, various styrylisoxazoles reacted smoothly with tosylmethyl isocyanide and analogs to deliver a wide range of 3-(isoxazol-5-yl)pyrroles at ambient temperature. This transformation is operationally simple, high-yiel...

Journal: :Journal of Porphyrins and Phthalocyanines 2004

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