نتایج جستجو برای: phosphorus ylides

تعداد نتایج: 42142  

Journal: :Organic & biomolecular chemistry 2011
Richard Herchl Martin Stiftinger Mario Waser

In comparison to the use of sulfur ylides, the use of ammonium ylides for the synthesis of epoxides is significantly less developed. As a part of our systematic investigations concerning the use of amide-stabilised ammonium ylides for the synthesis of glycidic amides we have focused on the identification of the best-suited amino leaving group for this purpose. Whereas tertiary amines like quinu...

2014
Natalie K. Machamer Xiaoxi Liu Stephen P. Waters

The first examples of azomethine ylides derived from allylic amine and glyoxal precursors are reported. The condensation of primary allylic and α-aryl amines with glyoxylates or α-aryl glyoxals affords conjugated azomethine ylides that undergo facile [3 + 2] cycloaddition, providing 5-alkenyl pyrrolidine cycloadducts that cannot be accessed through the classical use of amino esters as ylide pre...

Journal: :Organic & biomolecular chemistry 2006
Raphaël Robiette Matteo Conza Varinder K Aggarwal

Diastereoselectivity in reactions of aryl-stabilised ammonium ylides are highly sensitive to the nature of the amine and the ylide substituent. DFT calculations are consistent with a mechanism in which reversibility in betaine formation [despite the high energy (and therefore instability) of ammonium ylides] is finely balanced due to the high barrier to ring closure.

Journal: :Polymer Chemistry 2022

Readily available poly(sulfur ylides) are described as a new class of zwitterionic polymers that show distinct solution and thermal behavior.

Journal: :Organic & biomolecular chemistry 2014
Mehdi Abaszadeh Mohammad Seifi

Ultrasound irradiation can promote the 1,3-dipolar cycloaddition reaction of 2-chloropyridinium ylides with 2-benzylidenemalononitrile or 2,2'-(1,4-phenylenebis(methanylylidene))dimalononitrile, to afford the indolizine and bis-indolizine derivatives respectively. While the reaction of pyridinium ylides with 2-benzylidenemalononitrile or 2,2'-(1,4-phenylenebis(methanylylidene))dimalononitrile u...

2015
Marcel Mirel Popa Emilian Georgescu Mino R Caira Florentina Georgescu Constantin Draghici Raluca Stan Calin Deleanu Florea Dumitrascu

The three possible structural isomers of 4-(pyridyl)pyrimidine were employed for the synthesis of new pyrrolo[1,2-c]pyrimidines and new indolizines, by 1,3-dipolar cycloaddition reaction of their corresponding N-ylides generated in situ from their corresponding cycloimmonium bromides. In the case of 4-(3-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine the quaternization reactions occur as expect...

Journal: :Organic & biomolecular chemistry 2009
Guan-Wu Wang Ping Wu Hai-Tao Yang

The experimental results of the reaction of C60 with carbonyl ylides generated from trans-epoxides, which afforded cis-products exclusively or predominantly, can be explained well by computational investigation of the proposed reaction mechanism. Our theoretical calculations demonstrate that only cis-carbonyl ylides can be formed directly from trans-epoxides, in compliance with the Woodward-Hof...

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