نتایج جستجو برای: friedländer hetero annulation

تعداد نتایج: 5992  

2016
Rajith S. Manan Pinjing Zhao

Catalytic C-H activation and hydroamination represent two important strategies for eco-friendly chemical synthesis with high atom efficiency and reduced waste production. Combining both C-H activation and hydroamination in a cascade process, preferably with a single catalyst, would allow rapid access to valuable nitrogen-containing molecules from readily available building blocks. Here we repor...

Journal: :Angewandte Chemie 2014
Manh V Pham Nicolai Cramer

Larger condensed arenes are of interest owing to their electro- and photochemical properties. An efficient synthesis is the catalyzed aromatic annulation of a smaller arene with two alkyne molecules. Besides difunctionalized starting materials, directed C-H functionalization can be used for such aromatic homologation. However, thus far the requirement of either pre-functionalized substrates or ...

Journal: :Dalton transactions 2015
Priyam Bharadwaz Bitupon Borthakur Ashwini K Phukan

Theoretical calculations were carried out to understand the effect of annulation on the electronic and ligand properties of boron substituted N-heterocyclic carbenes (B-NHCs). Annulation results in a decrease in stability as indicated by the calculated values of singlet-triplet separations and stabilization energies as well as HOMO-LUMO gaps. Annulated B-NHCs are found to be weaker σ-donors but...

Journal: :Chemistry 2021

This review summarizes the results on aromaticity of a series synthesized and hypothetical neutral heterocirculene molecules their double charged ions. The heterocirculenes is direct reflection electronic structure responsible for specific optoelectronic photophysical properties. We show how presence heteroatom in outer macrocycle affects hetero[8]circulenes. In addition, we also describe chang...

2015
Sarah Yunmi Lee Yuji Fujiwara Atsuko Nishiguchi Marcin Kalek Gregory C. Fu

Substantial progress has been described in the development of asymmetric variants of the phosphine-catalyzed intermolecular [3+2] annulation of allenes with alkenes; however, there have not been corresponding advances for the intramolecular process, which can generate a higher level of complexity (an additional ring and stereocenter(s)). In this study, we describe the application of chiral phos...

Journal: :Organic & biomolecular chemistry 2008
Jonathan Sperry Jennifer S Gibson Jimmy J P Sejberg Margaret A Brimble

The enantioselective synthesis of a dimeric pyranonaphthoquinone closely related to the cardinalins is described. Whilst attempts to effect a double Hauser-Kraus annulation of enone 5 were unsuccessful using both bis-phthalide 4 and bis-sulfone 21, a single annulation of cyanophthalide 28 with enone 5 furnished functionalised naphthalene 31. Suzuki-Miyaura homocoupling of the aryl triflate 29 d...

Journal: :Advanced Synthesis & Catalysis 2022

Arylidene-Δ2-pyrrolin-4-ones undergo organocatalyzed annulation with malononitrile, furnishing dihydropyrano[3,2-b]pyrroles (18 examples, 0–77% ee in dichloromethane, 11–44% methanol). The products could be enantiomerically enriched by trituration (11 95–99% ee). Enantioselectivity was dependent on the nature of substrate and conformation catalyst, which turn solvent-controlled. reaction mechan...

2014
Brendan T. Parr Huw M. L. Davies

Stereoselective synthesis of a cyclopentane nucleus by convergent annulation constitutes a significant challenge for synthetic chemists. Although a number of biologically relevant cyclopentane natural products are known, more often than not, the cyclopentane core is assembled in a stepwise manner because of the lack of efficient annulation strategies. Here we report the rhodium-catalysed reacti...

1999
M. Fernanda N. N. Carvalho Armando J. L. Pombeiro Gabriele Wagner Rudolf Herrmann

Platinum(II) catalyzes the isomerization of camphor sulfonamide diynes in a cascade reaction involving annulation of a five-membered ring to the camphor skeleton, ring-enlargement by C-C bond cleavage, reduction of sulfur(VI) to sulfur(IV), and oxidation of a hydroxy group to a ketone. The reactions of the diynes with other transition metal compounds were also studied. Copper, gold and rhenium ...

2014
Oliviero Carugo

A large fraction of the proteome is made by proteins that are not permanently monomeric but form oligomeric assemblies, which can be either homo- or hetero-oligomeric. Here it is described that protomers of hetero-oligomeric proteins tend to resemble each other more than expected. This is verified by comparing the level of similarity of pairs of hetero-oligomeric protein protomers and of pairs ...

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