نتایج جستجو برای: regioselectivity
تعداد نتایج: 1520 فیلتر نتایج به سال:
In modern methods for the preparation of small molecules and polymers, the insertion of substrate carbon-carbon double bonds into metal-carbon bonds is a fundamental step of paramount importance. This issue is illustrated by Mizoroki-Heck coupling as the most prominent example in organic synthesis and also by catalytic insertion polymerization. For unsymmetric substrates H(2)C = CHX the regiose...
A novel heterogeneous catalysis system using metal-organic frameworks as catalyst demonstrated excellent chemo- and regioselectivity for the direct arylation of unactivated arenes with aryl iodides/bromides without the assistance of any transition metals.
Novel bidentate amidines were designed and synthesized as easily available electron-donating N-ligands for Ni0-mediated coupling of carbon dioxide with alkynes or allenes, and high regioselectivity was achieved even for the carboxylation of aryl substituted internal alkynes.
The [3 + 2] cycloaddition of alkynylboronates and azides provides a direct route to novel triazole boronic esters, the regioselectivity of this process and functionalisation of the heterocycle products is described.
An efficient iron-promoted alkylation of indoles with enamides has been accomplished under mild reaction conditions. The reaction proceeded with remarkable regioselectivity leading exclusively to substitution by indoles at α-position of enamides.
Using a family of novel mononuclear and dinuclear palladium complexes of phanephos ligands, the simultaneous control of regioselectivity and enantioselectivity in the hydroxycarbonylation and alkoxycarbonylation of styrene derivatives has been realised for the first time.
The first phosphine catalysed Michael addition of arylcyanoacetates to allenoates has been developed, and the β-selective products with a quaternary center were obtained in excellent yields. This unusual regioselectivity may open new opportunities to access interesting molecular structures.
Abstract Anilines selectively arylated at their ortho, meta or para positions are useful building blocks in synthesis and have found applications many areas. The most straightforward method for relies on the direct arylation of a C(sp2)–H bond anilines, an attractive strategy avoiding prefunctionalization starting anilines provided that such arylations proceed with high levels regioselectivity....
Tada! Highly functionalized chiral dibenzazepinones are obtained by a mild palladium(0)-catalyzed enantioselective C-H arylation with excellent selectivities by using simple taddol phosphoramidite ligands. The amide tether allows exclusive regioselectivity through a rare eight-membered palladacycle intermediate.
Some new bulky fluorinated diphosphines have been prepared and converted to palladium dichloride complexes that have been found to give increased regioselectivity and activity over other Pd-diphosphine systems when used as catalysts for hydroxycarbonylation of styrene.
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