نتایج جستجو برای: heck reaction

تعداد نتایج: 413170  

2017
Soham Maity Pravas Dolui Rajesh Kancherla Debabrata Maiti

Unactivated acyclic internal aliphatic olefins are often found to be unreactive in conventional alkenylation reactions. To address this problem, a cobalt catalyzed allylic selective dehydrogenative Heck reaction with internal aliphatic olefins has been developed. The method is highly regioand stereoselective, the conditions are mild and a wide variety of functional groups can be tolerated. Rema...

Journal: :Dalton transactions 2008
Michael Y Jiang Ji-Young Shin Brian O Patrick David Dolphin

A meso-palladioporphyrin intermediate was isolated from a Heck reaction between an iodoporphyrin and a non-activated olefin using a Pd(PPh3)2Cl2/Et3N system; its structure was characterized by NMR, MS and X-ray crystallography. Studies on its formation indicate that the Pd(II) catalyst was reduced in situ by Et3N with the assistance of water. The catalytic activity of the intermediate was confi...

Journal: :Chembiochem : a European journal of chemical biology 2007
Koichiro Kodama Seketsu Fukuzawa Hiroshi Nakayama Kensaku Sakamoto Takanori Kigawa Takashi Yabuki Natsuko Matsuda Mikako Shirouzu Koji Takio Shigeyuki Yokoyama Kazuo Tachibana

A new carbon-carbon bond has been regioselectively introduced into a target position (position 32 or 174) of the Ras protein by two types of organopalladium reactions (Mizoroki-Heck and Sonogashira reactions). Reaction conditions were screened by using a model peptide, and the stability of the Ras protein under the reaction conditions was examined by using the wild-type Ras protein. Finally, th...

Journal: :Journal of the American Chemical Society 2006
Jong S Park James N Wilson Kenneth I Hardcastle Uwe H F Bunz Mohan Srinivasarao

An acetylene dye rotaxane with alpha-CD has been synthesized using the Heck-Cassar-Sonogashira-Hagihara-type reaction in aqueous solution. Free dye with tetracarboxylic acids is found to be highly sensitive to various metal ions, showing high Stern-Volmer constants, KSV. As CD encapsulation protects and stabilizes the threaded chromophore against an outside quencher, metal-insensitive biologica...

Journal: :Angewandte Chemie 2014
Felix Klotter Armido Studer

Controlled access to resveratrol-based natural products is offered by a novel, modular concept. A common building block readily available on a large scale serves as the starting material for the introduction of structurally important aryl groups by a Pd-catalyzed decarboxylative arylation and an oxidative Heck reaction with good yields and high stereoselectivity. The modular approach is convinc...

Journal: :Organic & biomolecular chemistry 2005
Nikolai Kuhnert Adam Le-Gresley

Upper rim substituted tetraiodo calix[4]arenes are coupled to a variety of acrylamides using the palladium catalysed Heck reaction. Tetra-acrylamido upper rim substituted calix[4]arenes are obtained in good yields with exceptionally high stereoselectivity, to produce the all-trans isomers. Tetra-acrylamido calix[4]arenes derived from secondary acrylamides are shown to dimerise via eight hydroge...

2017
Emma E. Blackham Kevin I. Booker‐Milburn

A short, 5-step total synthesis of (±)-3-demethoxyerythratidinone from a simple pyrrole derivative is described. Features include the formation of gram quantities of a key tricylic aziridine from a challenging photochemical cascade reaction through the use of flow photochemistry. The final step involved a highly unusual Heck cyclization whereby ligand control enabled efficient formation of the ...

Journal: :Organic & biomolecular chemistry 2012
Sajjad Ahmad Michael D Swift Louis J Farrugia Hans Martin Senn Andrew Sutherland

A new synthetic approach has been developed for the preparation of 7-deoxypancratistatin analogues bearing a syn-(4aS,10bS)-phenanthridone ring junction. A one-pot tandem process involving a substrate-directed Overman rearrangement and ring closing metathesis reaction was developed for the stereoselective synthesis of a carbocyclic allylic trichloroacetamide. Conversion to a 6-bromopiperonyl am...

Journal: :Molecules 2010
Martin H G Prechtl Jackson D Scholten Jairton Dupont

A brief summary of selected pioneering and mechanistic contributions in the field of carbon-carbon cross-coupling reactions with palladium nanoparticles (Pd-NPs) in ionic liquids (ILs) is presented. Five exemplary model systems using the Pd-NPs/ILs approach are presented: Heck, Suzuki, Stille, Sonogashira and Ullmann reactions which all have in common the use of ionic liquids as reaction media ...

Journal: :The Journal of organic chemistry 2001
U Bhatt M Christmann M Quitschalle E Claus M Kalesse

The first total synthesis of ratjadone was achieved using a highly convergent approach joining three subunits together with a Wittig olefination and a selective Heck reaction as the pivotal steps. Besides establishing a robust and reliable route for the synthesis of this orphan ligand, the configuration of unknown stereocenters could also be determined. This synthesis not only provides an addit...

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