نتایج جستجو برای: annulation

تعداد نتایج: 988  

Journal: :Chemistry 2011
Łukasz Albrecht Lars Krogager Ransborg Anna Albrecht Lennart Lykke Karl Anker Jørgensen

This study demonstrates the first enantioselective synthesis of hydroxyalkyl- and aminoalkyl-substituted imidazoles, oxazoles, and thiazoles. The approach developed utilizes a highly effective one-pot reaction cascade that consists of either an organocatalytic epoxidation or aziridination of α,β-unsaturated aldehydes coupled with a [3+2]-annulation, in which amidines, ureas, or thioureas act as...

2012
Ai Guo Zhu Zhuo Ming Ma Lin Jie Li Tian Tian Wei Yan Qing Ge

The title compound, C(16)H(16)N(2)O(2), was synthesized using a novel tandem annulation reaction between 1-(1H-benzo[d]imidazol-2-yl)ethanone and ethyl (E)-4-bromo-but-2-enoate under mild conditions. The dihedral angles formed by the mean plane of the five-membered imidazole ring with the dihydro-pyridin and benzene rings are 1.54 (9) and 1.85 (9)°, respectively.

Journal: :Chemical communications 2015
Wen-Yang Gao Kunyue Leng Lindsay Cash Matthew Chrzanowski Chavis A Stackhouse Yinyong Sun Shengqian Ma

A series of prototypal metal-organic frameworks (MOFs) consisting of polyhedral cages with accessible Lewis-acid sites, have been systematically investigated for Friedländer annulation reaction, a straightforward approach to synthesizing quinoline and its derivatives. Amongst them MMCF-2 demonstrates significantly enhanced catalytic activity compared with the benchmark MOFs, HKUST-1 and MOF-505...

Journal: :Beilstein Journal of Organic Chemistry 2005
Oldřich Paleta Karel Pomeisl Stanislav Kafka Antonín Klásek Vladislav Kubelka

Substituted 3-(fluoroacyloxy)quinoline-2,4(1H,3H)-diones including 3-(fluoroiodoacetoxy) derivatives react with triethyl phosphite to afford either the product of the Perkow reaction or the corresponding 4-ethoxyquinolin-2(1H)-one. In both reactions, the fluorocarboxylate anion acts as the first observed leaving group. This observation restricts the application of the intramolecular Horner-Wads...

1999
MARIANA DA FONSECA CAVALCANTI MARIA CRISTINA DA SILVA

A new genus and species of Desmodoridae was found in deep-sea sediments of the Campos Basin. Although the cuticle annulation of the new species is similar to members of Desmodorinae, many morphological features are strong enough to classify it within the Spiriniinae. Spirodesma magdae nov. gen. nov. sp. is characterized mainly by the presence of a unique form of unispired amphids, with circular...

2015
Rebecca E. Johnson Tristan de Rond Vincent N. G. Lindsay Jay D. Keasling Richmond Sarpong

The enantiomers of the natural product cycloprodigiosin were prepared using an expedient five-step synthetic sequence that takes advantage of a Schöllkopf-Barton-Zard (SBZ) pyrrole annulation with a chiral isocyanoacetate and a nitrocyclohexene derivative. Using chiral HPLC and X-ray crystallographic analyses of the synthetically prepared material and natural isolate (isolated from the marine b...

Journal: :Journal of the American Chemical Society 2002
Andreas Lerchner Erick M Carreira

An efficient synthesis of the antitumor alkaloid (+/-)-strychnofoline is documented. Key to the development of the highly convergent strategy delineated is the coupling of a cyclic imine with spiro[cyclopropan-1,3'-oxindole], which takes place in a highly diastereoselective manner. The ability to conduct annulation reactions of spirocyclopropyloxindoles with functionalized cyclic imines provide...

Journal: :Organic & biomolecular chemistry 2014
Jiuxi Chen Jianjun Li Weike Su

The first example of the palladium-catalyzed one-pot synthesis of 2-arylbenzofurans in moderate to excellent yields via a tandem reaction of 2-hydroxyarylacetonitriles with sodium sulfinates is reported. A plausible mechanism for the formation of 2-arylbenzofurans involving desulfinative addition and intramolecular annulation reactions is proposed. Moreover, the present synthetic route to benzo...

2014
Blane P. Zavesky Nicholas R. Babij John P. Wolfe

A new method for the synthesis of 2-aminoimidazole products is described. The heterocyclic products are generated in good yields via Pd-catalyzed carboamination reactions of N-propargyl guanidines and aryl triflates. This methodology generates both a C-N and C-C bond during the annulation step and facilitates the rapid construction of 2-aminoimidazole products with different aryl groups. The ut...

2014
Xiaohong Pan Thomas D. Bannister

A general synthetic approach to β-carboline-containing alkaloids was developed. Two consecutive palladium-mediated processes, a Sonagashira coupling and a Larock indole annulation reaction, are central to the method. The scope of the approach was investigated and found to be amenable for constructing a variety of biologically significant natural products and also for preparing substituted analo...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید