نتایج جستجو برای: ketones

تعداد نتایج: 9200  

Journal: :Organic letters 2000
Nicolaou Vassilikogiannakis Kranich Baran Zhong Natarajan

A selective, mild, and highly efficient method has been uncovered during the total synthesis of the CP molecules to accomplish the one-carbon homologation of sterically hindered aldehydes in the presence of acid- and base-labile moieties, Michael acceptors, and even other carbonyl groups such as reactive and epimerizable ketones. Mechanistic studies have revealed a neutral reagent for the rapid...

2004
Han-Xun Wei Richard L. Jasoni Huawu Shao Jiali Hu Paul W. Paré

The first example of a direct aldehyde–ketone coupling using the secondary amine piperidine as base in the presence of MgI2 to generate high selectivity of anti-aldol products from unmodified ethyl ketones in high yield is reported. The coupling reactions were carried out in a one-pot reaction by mixing four reaction components at room temperature. In the case of unsymmetrical ketones, addition...

2013
Seyed Mohammad Vahdat Samad Khaksar Saeed Baghery

Ionic liquid with multi-SO H groups was employed as a catalyst for facile preparation of 3 bis(indolyl)methanes via the one-pot condensation of indole with aldehydes or ketones. Various aliphatic and aromatic aldehydes or ketones were utilized in the reaction and in all situations the desired product were synthesized successfully. The described novel synthesis method propose several advantages ...

Journal: :Molecules 2017
Alexander Anis'kov Irina Klochkova Roman Tumskiy Alevtina Yegorova

For the first time, arylmethylidene cyclohexanones that are non-symmetrical due to the presence of peripheral substituents were studied in 1,3-dipolar cycloaddition reactions. It is shown that the interaction with the azomethine ylide generated from sarcosine proceeds regio- and diastereoselectively, with the participation of two non-equivalent parts of the dipolarophile. Also for the first tim...

Journal: :Chemical communications 2015
Kazuhiro Yoshida Takumi Kamimura Hiroshi Kuwabara Akira Yanagisawa

A diverse series of chiral bicyclic NHC/Ir complexes were prepared via a previously developed divergent synthesis of chiral imidazolium salts. Among the complexes, 8dz was found to be an excellent catalyst precursor for the Ir-catalyzed asymmetric transfer hydrogenation of ketones. The reaction of ketones with 8dz proceeded smoothly to give corresponding alcohols with high enantioselectivities ...

Journal: :Chemical communications 2015
Xiao Liang Kun Wei Yu-Rong Yang

The unified Ir-catalyzed enantioselective allylic substitution reactions of silyl enol ethers derived from ketones and α,β-unsaturated ketones with branched, racemic allylic alcohols are described. This transformation is catalyzed by the Carreira system and proceeds without fluoride, and with high ee and b : l ratio. The synthetic utility of this method was illustrated by the concise enantiosel...

Journal: :Chemical & pharmaceutical bulletin 2009
Qian Chen Masami Kuriyama Xinyu Hao Takahiro Soeta Yasutomo Yamamoto Ken-Ichi Yamada Kiyoshi Tomioka

A catalytic asymmetric conjugate arylation of acyclic alpha,beta-unsaturated ketones with arylboronic acids was catalyzed by 3 mol% of chiral amidomonophosphane 1-rhodium(I) in the presence of potassium hydroxide in a mixture of 1,4-dioxane and water at 70 degrees C to afford 1,4-conjugate arylated acyclic ketones with high enantiomeric excess in high chemical yield. Thirteen examples of the re...

2004
Bruhaspathy Miriyala Sukanta Bhattacharyya John S. Williamson

An efficient, general procedure for highly chemoselective reductive mono-alkylation of ammonia with ketones is reported. Treatment of ketones with ammonia in ethanol and titanium(IV) isopropoxide, followed by in situ sodium borohydride reduction, and a straightforward workup afforded primary amines in good to excellent yields. Reductive alkylation of ammonia with aldehydes, on the other hand, a...

Journal: :Organic & biomolecular chemistry 2012
Andrei V Malkov Angus J P Stewart-Liddon Grant D McGeoch Pedro Ramírez-López Pavel Kočovský

A new family of Lewis basic 2-pyridyl oxazolines have been developed, which can act as efficient organocatalysts for the enantioselective reduction of prochiral aromatic ketones and ketimines with trichlorosilane, a readily available and inexpensive reagent. 1-Isoquinolyl oxazoline, derived from mandelic acid, was identified as the most efficient catalyst of the series, capable of delivering hi...

Journal: :Organic letters 2003
Naidu S Chowdari D B Ramachary Carlos F Barbas

[reaction: see text] l-Proline catalyzed the enzyme-like direct asymmetric assembly of aldehydes, ketones, and azodicarboxylic acid esters to provide optically active beta-amino alcohols. This assembly reaction uses both aldehydes and ketones as donors in one pot. The aldol-derived stereocenter is formed with a reduced facial selectivity in reactions involving (R)-amino aldehydes. The reactions...

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