نتایج جستجو برای: regioselectivity

تعداد نتایج: 1520  

Journal: :Chemical and Pharmaceutical Bulletin 1997

Journal: :Bulletin of the Chemical Society of Japan 1984

Journal: :The Journal of organic chemistry 2013
Yi-Yun Yu Lei Bi Gunda I Georg

A ligand-free method for the Pd-catalyzed direct arylation of cyclic enaminones using aryl iodides was developed. This method can be applied to a wide range of cyclic enaminones and aryl iodides with excellent C5-regioselectivity. Using widely available aryl iodides, the generality of this transformation provides easy access to a variety of 3-arylpiperidine structural motifs.

Journal: :Organic & biomolecular chemistry 2011
Anahit Pews-Davtyan Matthias Beller

A general synthesis of 3-amidoindoles from easily available arylhydrazines and acylated propargylamines is described. In the presence of inexpensive Zn salts, alkyne amination and subsequent Fischer indole-cyclization took place in good yields with excellent regioselectivity providing an interesting scaffold for potentially bio-active compounds.

Journal: :Organic & biomolecular chemistry 2015
Jinwei Sun Fuyao Wang Yongmiao Shen Huizhen Zhi Hui Wu Yun Liu

A direct and regioselective C1-acyloxylation of indolizines was developed via palladium-catalyzed C-H functionalization. A series of indolizines were successfully acyloxylated at the C1 position with the tolerance of a broad range of functional groups. In this reaction, high regioselectivity was achieved in the absence of a directing group. This work represents the first example of indolizine a...

Journal: :Chemical communications 2015
Katharina Schmölzer Tibor Czabany Christiane Luley-Goedl Tea Pavkov-Keller Doris Ribitsch Helmut Schwab Karl Gruber Hansjörg Weber Bernd Nidetzky

Structure-guided active-site redesign of a family GT-80 β-D-galactoside sialyltransferase (from Pasteurella dagmatis) to change enzyme regioselectivity from α-2,3 in the wild type to α-2,6 in a P7H-M117A double mutant is reported. Biochemical data for sialylation of lactose together with protein crystal structures demonstrate highly precise enzyme engineering.

Journal: :Bioscience, biotechnology, and biochemistry 2008
Kumi Sugino Hiroshi Yoshimura Toshio Nishikawa Minoru Isobe

Regioselectivity of Larock indole synthesis, a palladium-catalyzed heteroannulation between o-iodoaniline and internal acetylene, was estimated using acetylenes substituted with ester and/or Boc-protected amine at the homopropargylic position and with perbenzyl- and unprotected glucose. Low to moderate regioselectivities were observed in all the cases, indicating these functional groups do not ...

Journal: :Chemical communications 2014
Clemens J von Bühler Vlada B Urlacher

A P450 monooxygenase from Nocardia farcinica (CYP154A8) catalyses the stereo- and regioselective hydroxylation of n-alkanes, still a challenging task in chemical catalysis. In a biphasic reaction system, the regioselectivity for the C2-position of C7-C9 alkanes was over 90%. The enzyme showed strict S-selectivity for all tested substrates, with enantiomeric excess (ee) of up to 91%.

Journal: :Organic letters 2016
Hai-Tao Zhu Sen Ke Ni-Ni Zhou Ming-Jin Fan De-Suo Yang

The development of intermolecular [2 + 2]-cycloaddition of α-iodo-unsaturated ketones in the presence of diisobutylaluminum hydride (Dibal-H) is reported to produce various trispirocyclic derivatives containing a cyclobutane ring. This sequential lactonization/[2 + 2]-cycloaddition proceeds in high regioselectivity under mild conditions.

Journal: :Journal of the American Chemical Society 2013
Marie-Gabrielle Braun Abigail G Doyle

The first catalytic allylic C-H fluorination reaction using a nucleophilic fluoride source is reported. Under the influence of a Pd/Cr cocatalyst system, simple olefin substrates undergo fluorination with Et3N·3HF in good yields with high branched:linear regioselectivity. The mild conditions and broad scope make this reaction a powerful alternative to established methods for the preparation of ...

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