نتایج جستجو برای: 5 tri substituted imidazoles

تعداد نتایج: 1262691  

Journal: :Chemical communications 2006
Christian Löfberg Ronald Grigg Ann Keep Andrew Derrick Visuvanathar Sridharan Colin Kilner

Microwave assisted indirect functionalization of alcohols with 1,3-dimethylbarbituric acid followed by spirocyclisation employing a sequential one-pot Ir(III)/Pd(0) catalysed process, involving the formation of three new C-C bonds, one spirocyclic ring and one di- or tri-substituted exocyclic alkene, is described.

Journal: :Chemical communications 2011
Sheung Chun To Fuk Yee Kwong

A new family of phosphine ligands bearing a bulky carbazolyl scaffold is described. With the combination of ligand 2a and Pd(OAc)(2), difficult tri-ortho-substituted biaryl couplings are accomplished smoothly. In particular, the catalyst loading as low as 0.02 mol% of Pd for non-activated 2,6-disubstituted aryl chloride coupling can be achieved.

Journal: :Chemical communications 2015
Zhen-Hua Wang Zhi-Jun Wu Xue-Qun Huang Deng-Feng Yue Yong You Xiao-Ying Xu Xiao-Mei Zhang Wei-Cheng Yuan

The diastereo- and enantioselective direct vinylogous Michael addition reaction of γ-substituted butenolides to 2-enoylpyridines has been achieved. A range of γ,γ-disubstituted butenolide derivatives, bearing two consecutive tri- and tetrasubstituted stereogenic centers, were readily obtained in good yields with excellent stereoselectivities (up to >99 : 1 dr and >99% ee).

Journal: :Dalton transactions 2016
Ewan R Clark Andryj M Borys Kyle Pearce

Paradoxically, N- and O-donor substituted tri-arylphosphanes are shown to be weaker donors than PPh3 when binding the soft Lewis acid moiety [PPh2]+. This arises from internal solvation and rehybridisation at phosphorus, precluding chelation and increasing steric demand, in direct contrast to coordination modes observed for metal complexes.

Journal: :Applied sciences 2021

This study develops a process for enhancing the photostabilization of PVC films blended with low concentration mefenamate–tin complex. One tri-substituted and three di-substituted organotin complexes containing mefenamate unit are synthesized, their chemical structures established. The reactions mefenamic acid number substituted tin chlorides gave corresponding in 70–77% yields. Tin were thin f...

2011
Jennifer A. Harrison K. P. Ravindranathan Kartha Eric J. L. Fournier Todd L. Lowary Carles Malet Ulf J. Nilsson Ole Hindsgaul Sergio Schenkman James H. Naismith Robert A. Field

Systematically modified octyl galactosides and octyl N-acetyllactosamines were assessed as inhibitors of, and substrates for, T. cruzi trans-sialidase (TcTS) in the context of exploring its acceptor substrate binding site. These studies show that TcTS, which catalyses the α-(2→3)-sialylation of non-reducing terminal β-galactose residues, is largely intolerant of substitution of the galactose 2 ...

Journal: :Advanced Synthesis & Catalysis 2021

A diastereoselective and enantioselective construction of 2,3-disubstituted 1,4-dicarbonyl compounds is reported. Nishiyama's RuPhebox complex (2.0 mol% catalyst loading) serves as a chiral Lewis acid in conjunction with BrCCl3 base for the oxidative homocoupling 2-acyl imidazoles via stereocontrolled reaction intermediate Ru enolates situ brominated imidazoles. Cleavage achiral imidazole auxil...

Journal: :Organometallics 2021

An efficient synthesis of 1,1?,2,2?-tetraiodoferrocene is described that uses 1,1?,2,2?-tetrakis(tri-n-butylstannyl)ferrocene as a key intermediate in its synthesis. In an attempt to examine the stepwise mechanism, reaction tetratin-substituted ferrocene with iodine was monitored by 1H NMR and series coexisting compounds such 1,1?-bis(tri-n-butylstannyl)-2,2?-diodoferrocene were observed. The c...

Journal: :Journal of the American Chemical Society 2007
David A Evans Keith R Fandrick Hyun-Ji Song Karl A Scheidt Risheng Xu

The enantioselective Friedel-Crafts addition of a variety of indoles catalyzed by bis(oxazolinyl)pyridine-scandium(III) triflate complexes (Sc(III)-pybox) was accomplished utilizing a series of beta-substituted alpha,beta-unsaturated phosphonates and alpha,beta-unsaturated 2-acyl imidazoles. The acyl phosphonate products were efficiently transformed into esters and amides, whereas the acyl imid...

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