Notizen: Reactions of Harmaline and its Derivatives, V A one-Step Synthesis of Reserpine Analogues

1976 ◽  
Vol 31 (4) ◽  
pp. 533-534 ◽  
Author(s):  
Atta Rahman ◽  
Sadiqa Firdous ◽  
Anwer Basha
Keyword(s):  
One Step ◽  
High Yields ◽  
Cyclohexanone Derivative

The reaction of harmaline with the cyclohexanone derivative (4) affords the reserpine analogue (5) in high yields, thus providing a one step approach to such pharmacologically important substances.

scholarly journals PEG-embedded KBr3: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

2011 ◽  
Vol 7 ◽  
pp. 1334-1341 ◽  
Author(s):  
Sanny Verma ◽  
Suman L Jain ◽  
Bir Sain
Keyword(s):  
Coupling Reaction ◽  
Recyclable Catalyst ◽  
Efficient Synthesis ◽  
Molecular Bromine ◽  
Keto Ester ◽  
One Step ◽  
High Yields ◽  
Multicomponent Coupling ◽  
Three Component Coupling

PEG-embedded potassium tribromide ([K+PEG]Br3 −) was found to be an efficient and recyclable catalyst for the synthesis of functionalized piperidines in high yields in a one step, three component coupling between aldehyde, amine and β-keto ester. At the end of the reaction the [K+PEG]Br3 − was readily regenerated from the reaction mixture by treating the residue containing [K+PEG]Br− with molecular bromine.

scholarly journals Amphiphilic Biaryl Monophosphine Ligands by Regioselective Sulfonation

2020 ◽  
Author(s):  
Jacob Rodriguez ◽  
Heemal Dhanjee ◽  
Stephen L. Buchwald
Keyword(s):  
Sulfuric Acid ◽  
Chromatographic Purification ◽  
Organometallic Reactions ◽  
One Step ◽  
High Yields

<div> <p>Amphiphilic ligands are valued for their ability to facilitate organometallic reactions in the presence of water. The regioselective sulfonation of a series of commercially available biaryl monophosphines to generate amphiphilic ligands is presented. In this one-step protocol, the temperature and addition of fuming sulfuric acid were carefully controlled to arrive at sulfonated biaryl monophosphine ligands in high yields with >95% regioselectivity without the need for chromatographic purification.</p> </div>

scholarly journals New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

2015 ◽  
Vol 11 ◽  
pp. 1175-1186 ◽  
Author(s):  
Rym Hassani ◽  
Mahjoub Jabli ◽  
Yakdhane Kacem ◽  
Jérôme Marrot ◽  
Damien Prim ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spectroscopic Analysis ◽  
Palladium Complexes ◽  
X Ray Diffraction ◽  
Factors Affecting ◽  
Enantiomerically Pure ◽  
One Step ◽  
Uv Visible ◽  
High Yields

The present paper describes the synthesis of new palladium–oxazoline complexes in one step with good to high yields (68–95%). The oxazolines were prepared from enantiomerically pure α-aminoalcohols. The structures of the synthesized palladium complexes were confirmed by NMR, FTIR, TOFMS, UV–visible spectroscopic analysis and X–ray diffraction. The optical properties of the complexes were evaluated by the determination of the gap energy values (E g) ranging between 2.34 and 3.21 eV. Their catalytic activities were tested for the degradation of Eriochrome Blue Black B (a model of azo dyes) in the presence of an ecological oxidant (H2O2). The efficiency of the decolorization has been confirmed via UV–visible spectroscopic analysis and the factors affecting the degradation phenomenon have been studied. The removal of the Eriochrome reached high yields. We have found that the complex 9 promoted 84% of color elimination within 5 min (C 0 = 30 mg/L, T = 22 °C, pH 7, H2O2 = 0.5 mL) and the energetic parameters have been also determined.

scholarly journals N-Heterocyclic carbene-catalyzed enantioselective hetero-[10 + 2] annulation

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Qiupeng Peng ◽  
Shi-Jun Li ◽  
Bei Zhang ◽  
Donghui Guo ◽  
Yu Lan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Higher Order ◽  
Heterocyclic Carbenes ◽  
Wide Scope ◽  
Functional Theory ◽  
One Step ◽  
High Yields ◽  
Powerful Strategy

AbstractHigher-order cycloadditions are a powerful strategy for the construction of polycycles in one step. However, an efficient and concise version for the induction of asymmetry is lacking. N-heterocyclic carbenes are widely used organocatalysts for asymmetric synthesis and could be an ideal choice for enantioselective higher-order cycloadditions. Here, we report an enantioselective [10 + 2] annulation between catalytically formed aza-benzofulvene intermediates and trifluoromethyl ketone derivatives. This protocol exhibits a wide scope, high yields, and good ee values, reflecting a robust and efficient higher-order cycloaddition. Density functional theory calculations provide an accurate prediction of the reaction enantioselectivity, and in-depth insight to the origins of stereocontrol.

Conversion of hydroxyl groups into bromo groups in carbohydrates with inversion of configuration

1981 ◽  
Vol 59 (2) ◽  
pp. 339-343 ◽  
Author(s):  
Björn Classon ◽  
Per J. Garegg ◽  
Bertil Samuelsson
Keyword(s):  
Elevated Temperature ◽  
Hydroxyl Groups ◽  
Secondary Hydroxyl ◽  
Reaction Proceeds ◽  
One Step ◽  
High Yields

A novel reagent system is described for the efficient, one-step transformation of hydroxyl groups in carbohydrates to bromodeoxy groups. The reaction proceeds with inversion of configuration. The reagent system consists of triphenylphosphine, tribromoimidazole, and imidazole in toluene at elevated temperature. The carbohydrate need not be soluble in toluene. The examples given include substitution of isolated primary and secondary hydroxyl groups in otherwise protected carbohydrates as well as disubstitution involving one primary and one secondary position in hexopyranosides. High yields are obtained in the replacement of hydroxyl by bromine in the 2-position of 3,4,6-protected methyl α-D-gluco- and -mannopyranosides.

scholarly journals A Novel One-step Synthesis of Quinoline-2(1H)-thiones and Selones by Treating 3-Aryl-3-(2-aminophenyl)-1-propyn-3-ols with a Base and Elemental Sulfur or Selenium

2015 ◽  
Vol 10 (6) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Kazuaki Shimada ◽  
Hironori Izumi ◽  
Koki Otashiro ◽  
Kensuke Noro ◽  
Shigenobu Aoyagi ◽  
...  
Keyword(s):  
Elemental Sulfur ◽  
Reactive Species ◽  
Nucleophilic Attack ◽  
Amino Group ◽  
One Step ◽  
High Yields

A one-step conversion of 3-aryl-3-(2-aminophenyl)-1-propyn-3-ols into quinoline-2(1 H)-thiones and quinoline-2(1 H)-selones was achieved only by treating the substrates with n-butyllithium and either elemental sulfur or selenium, respectively. The reactions were assumed to proceed through an intramolecular nucleophilic attack of the neighboring amino group to the plausible in situ generated reactive species related to chalcogenoketenes. The subsequent mCPBA oxidation of quinoline-2(1 H)-selones afforded quinolin-2(1 H)-ones in high yields.

The decomposition of some organophosphorus insecticides and related compounds in plants

1955 ◽  
Vol 239 (663) ◽  
pp. 191-214 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Organophosphorus Compounds ◽  
Degradation Products ◽  
Parent Compound ◽  
The Other ◽  
Acidic Group ◽  
Water Partition Coefficient ◽  
Unknown Structure ◽  
One Step ◽  
High Yields

To discover the reactions undergone in plants by organophosphorus compounds of the type used as insecticides the non-ionizable metabolites of several compounds were studied. Octamethylpyrophosphoramide (schradan) is degraded in four species of plants. Low yields of heptamethylpyrophosphoramide and a powerful anticholinesterase are obtained besides ionizable compounds. Oxidation of schradan with hydrogen peroxide and with oxygenated liver slices gives the same products in similar proportions. Thus plants probably degrade schradan by oxidation, producing mainly compounds unstable in water, which are hydrolyzed to substituted phosphoric acids. The powerful anticholinesterase is believed to be hydroxymethyl-heptamethylpyrophosphoramide from its chloroform/water partition coefficient and its yield in plants. It may, however, be octamethylpyrophosphoramidic oxide. Turnip plants also degrade the dimethylamide, monomethylamide, n -butylamide, iso propylamide and ethyl ester of tetramethylphosphorodiamidic acid. As these compounds contain no acidic group which can be removed by hydrolysis after oxidation, high yields of compounds extractable from water by chloroform are obtained. None of the parent compounds are hydrolyzed, nor are butyl or wopropyl groups removed in one step. Probably the dimethylamide is demethylated to the monomethylamide in a way similar to schradan. The physical properties of the degradation products of the other compounds indicate that only the dimethylamido groups are attacked, the other groups being inert. OO -diethyl O -ethylthioethyl phosphorothionate is converted in plants to at least three compounds extractable by chloroform. Their structures are unknown. OO -diethyl S -ethylthioethyl phosphorothiolate is oxidized rapidly in plants to OO -diethyl S -ethylsulphinylethyl phosphorothiolate and another compound of unknown structure, both of which are more stable in plants than the parent compound. The same products are formed by the action of hydrogen peroxide on the parent compound. Thus a number of organophosphorus compounds are degraded by oxidation in plants. There is no evidence that their hydrolysis is catalyzed.

scholarly journals One-Step Synthesis of Acylboron Compounds via Cu-Catalyzed Carbonylative Borylation of Alkyl Halides

2020 ◽  
Author(s):  
Cheng Li-Jie ◽  
Zhao Siling ◽  
Neal Mankad
Keyword(s):  
Alkyl Halides ◽  
Efficient Synthesis ◽  
Mechanistic Studies ◽  
Acyl Halide ◽  
Reaction Conditions ◽  
One Pot ◽  
One Step ◽  
High Yields ◽  
Tertiary Alkyl

A Cu-catalyzed carbonylative borylation of unactivated alkyl halides has been developed, enabling efficient synthesis of aliphatic potassium acyltrifluoroborates (KATs) in high yields by treating the in-situ formed tetracoordinated acylboron intermediates with aqueous KHF2. A variety of functional groups are tolerated under the mild reaction conditions, and primary, secondary and tertiary alkyl halides are all applicable. In addition, this method also provides facile access to N-methyliminodiacetyl (MIDA) acylboronates as well as α-methylated potassium acyltrifluoroborates in a one-pot manner. Mechanistic studies indicate a radical atom transfer carbonylation (ATC) mechanism to form acyl halide intermediates that are subsequently borylated by (NHC)CuBpin.<br>

scholarly journals Rational Enzyme Design Without Structural Knowledge: A Sequence-Based Approach for Efficient Generation of Glycosylation Catalysts

2020 ◽  
Author(s):  
David Teze ◽  
Zhao, Jiao ◽  
Mathias Wiemann ◽  
Zubaida Gulshan Kazi ◽  
Rossana Lupo ◽  
...  
Keyword(s):  
Amino Acids ◽  
Glycoside Hydrolase ◽  
Enzyme Engineering ◽  
Glycoside Hydrolases ◽  
Structural Knowledge ◽  
Enzyme Design ◽  
Engineering Approach ◽  
Efficient Generation ◽  
One Step ◽  
High Yields

<p>We present an enzyme engineering approach based solely on amino-acids sequence to convert glycoside hydrolases into transglycosylases. We demonstrate its effectiveness on enzymes form five different glycoside hydrolase families, synthesizing various oligosaccharides containing different α-/β-pyranosides or furanosides in one-step with high yields.</p>

scholarly journals A New Method for the Synthesis of 2-Substituted Benzoxazoles from 2-Nitrophenol Derivatives and Aldehydes  

2021 ◽  
Vol 31 (3) ◽  
pp. 43-46
Keyword(s):  
Biological Activities ◽  
Catalyst System ◽  
Biologically Active ◽  
New Method ◽  
Redox Catalyst ◽  
High Pressure High Temperature ◽  
One Step ◽  
High Yields ◽  
Strong Acids ◽  
Single Reaction

Benzoxazole derivatives are one of the compounds with many interesting biological activities. Conventional methods are often performed under complex conditions using strong acids, expensive metal catalysts, requiring high pressure, high temperature, and under microwave irradiation. In this study, we reported a new method of benzoxazole synthesis with redox catalyst using FeCl3.6H2O and sulfur. This is a suitable, efficient, readily available and environmentally friendly catalyst system for redox and condensation reactions in one step at 100 oC. Applying this new method, we have synthesized eight 2-arylbenzoxazole derivatives with high yields (calculated according to 2-nitrophenol). This research is an important step forward in the synthesis of biologically active compounds containing the benzoxazole framework from readily available starting materials in a single reaction.

Sign in / Sign up

Export Citation Format

Share Document