نتایج جستجو برای: phosphorus ylide

تعداد نتایج: 41924  

2016
Chandra Shekar Reddy Pazhamalai Anbarasan

An efficient diastereoselective rhodium catalyzed synthesis of indolines possessing two contiguous tetrasubstituted carbon centers has been achieved with good to excellent yields using ortho-vinylanilines and iminocarbenes derived from N-sulfonyl-1,2,3-triazoles. The reaction affords excellent cisdiastereoselectivity through the initial formation of a N-ylide followed by intramolecular trapping...

Journal: :Molecules 2005
F Dumitrascu M R Caira C Draghici M T Caproiu A Badoiu

The 3+2 cycloaddition reaction of 1-(4-phenylphenacyl)-1,10-phenanthrolinium ylide 4 with activated alkynes gave pyrrolo[1,2- 4a][1,10]phenanthrolines 6a-d. The "one pot" synthesis of 6a,b,d from 4, activated alkenes, Et(3)N and tetrakis-pyridine cobalt (II) dichromate (TPCD) is described. The helical chirality of pyrrolophenanthrolines 6b-d was put in evidence by NMR spectroscopy.

Journal: :Organic & Biomolecular Chemistry 2015

Journal: :Journal of the American Chemical Society 2005
Ming Ma Lingling Peng Changkun Li Xiu Zhang Jianbo Wang

A highly stereoselective [2,3]-sigmatropic rearrangement of sulfur ylide generated through Cu(I) carbene and allyl and propargyl sulfides by a double asymmetric induction approach that combines a chiral camphor sultam auxiliary and Cu(I) catalyst with chiral or achiral diimine ligands has been developed.

Journal: :Chemical communications 2012
Anup Biswas Suman De Sarkar Ludger Tebben Armido Studer

Carbene catalysed redox activation of α,β-unsaturated aldehydes is applied for generation of α,β-unsaturated acyl azoliums which undergo cyclopropanation upon reaction with a sulfur ylide and an alcohol to give the corresponding cyclopropanecarboxylic acid esters. With chiral carbenes good to excellent diastereo and enantioselectivities are obtained.

2012
Alan Armstrong Alexandra Ferguson

tert-Butyl cinnamates are aziridinated with high trans-selectivity by an N-N ylide generated in situ from N-methylmorpholine and O-diphenylphosphinyl hydroxylamine. The resulting N-unfunctionalised aziridines are shown to be versatile synthetic building blocks that undergo highly selective ring-opening reactions with a wide range of nucleophiles.

2018
Oleksandr Zhurakovskyi Yunus E Türkmen Lorenz E Löffler Vijayalakshmi A Moorthie C Chun Chen Michael A Shaw Mark R Crimmin Marco Ferrara Mushtaq Ahmad Mehrnoosh Ostovar Johnathan V Matlock Varinder K Aggarwal

A convergent, nine-step (LLS), enantioselective synthesis of α-cyclopiazonic acid and related natural products is reported. The route features a) an enantioselective aziridination of an imine with a chiral sulfur ylide; b) a bioinspired (3+2)-cycloaddition of the aziridine onto an alkene; and c) installation of the acetyltetramic acid by an unprecedented tandem carbonylative lactamization/N-O c...

Journal: :Angewandte Chemie 2012
Masahiro Terada Yasunori Toda

Carbonyl ylides are generally non-isolable reactive intermediates and have been extensively utilized as the dipole in 1,3-dipolar cycloaddition reactions with electron-deficient and electron-rich dipolarophiles to afford polycyclic compounds including five-membered oxacycles. The most efficient method for generating the carbonyl ylide is the interaction of a metal carbene complex with the oxyge...

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: :Dalton transactions 2015
Sadayuki Arimori Masahiro Takada Norio Shibata

Trifluoromethylsulfinyl and trifluoromethylthio groups are both important substituents for pharmaceuticals, agrochemicals and functional materials. We herein report the trifluoromethylthiolation of allyl alcohols 2 with trifluoromethanesulfonyl hypervalent iodonium ylide 1 under copper catalysis to provide trifluoromethylsulfinyl compounds 3. Trifluoromethylthiolation of boronic acids 4 with 1 ...

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