نتایج جستجو برای: dielsalder cycloaddition

تعداد نتایج: 4580  

Journal: :Organic & biomolecular chemistry 2010
Cevher Altuğ Yasar Dürüst Mark C Elliott Benson M Kariuki Tillique Rorstad Mark Zaal

Alkylidenepyrrolidines 1, 21, 24 and 26 undergo reactions with nitrile oxides and nitrilimines or their precursors to give a range of novel heterocyclic compounds. With alkylidenepyrrolidine ester 1, nitrolic acids give products in which the liberated nitrous acid reacts with the alkylidenepyrrolidine, followed by two cycloadditions to give adducts 3. In contrast, hydroximoyl chlorides give iso...

2013
Carsten S Kramer Stefan Bräse

A variety of organocatalysts were screened for the catalysis of the naphthoquinone monoketal Diels-Alder reaction. In this study we found that Schreiner's thiourea catalyst 10 and Jacobson's thiourea catalyst 12 facilitate the cycloaddition of the sterically hindered naphthoquinone monoketal dienophile 3 with diene 4. The use of thiourea catalysis allowed for the first time the highly selective...

2004
Richard Jaffe Jie Han

Considerable progess has been made in recent years in chemical functionalization of fullerene molecules [see, for example: Taylor 93, and Diederich 96]. In some cases, the predominant reaction products are different from those obtained (using the same reactants) from polycyclic aromatic hydrocarbons (PAHs). One such example is the cycloaddition of o-benzyne to C60. It is well established that b...

Journal: :Angewandte Chemie 2015
Jan O Mueller Friedrich G Schmidt James P Blinco Christopher Barner-Kowollik

A rapid and catalyst-free cycloaddition system for visible-light-induced click chemistry is reported. A readily accessible photoreactive 2H-azirine moiety was designed to absorb light at wavelengths above 400 nm. Irradiation with low-energy light sources thus enables efficient small-molecule synthesis with a diverse range of multiple-bond-containing compounds. Moreover, in order to demonstrate ...

Journal: :Organic & biomolecular chemistry 2005
Zoltán Kaleta Orsolya Egyed Tibor Soós

Highly efficient fluorous tagging methodology was developed based on catalytic 1,3-dipolar cycloaddition as the key step.

Journal: :Chemical communications 2010
Frédéric Lincker Philippe Bourgun Helen Stoeckli-Evans Isabel M Saez John W Goodby Robert Deschenaux

A synthetic methodology based on the 1,3-dipolar cycloaddition reaction was developed to design enantiomerically pure liquid-crystalline fullerodendrimers.

Journal: :Angewandte Chemie 2021

The intramolecular [4+2] cycloaddition between arenes and allenes first reported by Himbert gives rapid access to rigid polycyclic scaffolds. Herein, we report a one-pot oxyalkynylation/cycloaddition reaction proceeding under mild conditions (23–90 °C) providing complex architectures with high efficiency, atom step economy. bicyclo[2.2.2]octadiene products were obtained wide variety of useful f...

Journal: :Organic & biomolecular chemistry 2009
Sung-Hyun Yang G R Clark Vittorio Caprio

An efficient and flexible synthetic approach to the core structures of pinnaic acid and halichlorine is described using spirocyclic nitrone 4 as a key intermediate. 1,3-Dipolar cycloaddition of 4 with dipolarophile 8 provides access to the azaspirocyclic core of pinnaic acid 5 while the spiroquinolizidine core of halichlorine 6 has been synthesised via cycloaddition of 4 with dipolarophile 29. ...

2016
Ryo Shintani Ryo Takano Kyoko Nozaki

A rhodium-catalyzed regioand enantioselective synthesis of silicon-stereogenic silicon-bridged arylpyridinones has been developed through [2 + 2 + 2] cycloaddition of silicon-containing prochiral triynes with isocyanates. High yields and enantioselectivities have been achieved by employing an axially chiral monophosphine ligand, and this process could be applied to catalytic asymmetric synthesi...

Journal: :Organic & biomolecular chemistry 2011
Sujit Mondal Ram Naresh Yadav Subrata Ghosh

Cu(I)-catalysed [2 + 2] photocycloaddition of 1,6-dienes embedded in a furano sugar is described in connection to a synthetic approach to an abnormal marine prostanoid tricycloclavulone. An unprecedented influence of remote substituents on the reactivity and stereoselectivity of the photocycloaddition reaction has been uncovered during this investigation. While an alkene substituent inhibits cy...

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