Neighboring phenolic group-activated gem-difluoroallylboration of imines for the catalyst-free synthesis of gem-difluorohomoallylamines

2018 ◽  
Vol 16 (18) ◽  
pp. 3367-3371 ◽  
Author(s):  
Xing Yang ◽  
Feng Zhang ◽  
Yang Zhou ◽  
Yi-Yong Huang
Keyword(s):  
Protecting Group ◽  
Catalyst Free ◽  
Wide Range ◽  
Phenolic Group ◽  
Imine Allylation

An unprecedented imine allylation with pinacol gem-difluoroallylborates for the synthesis of a wide range of racemic gem-difluorohomoallylamine derivatives under catalyst-free conditions was enabled by a neighboring phenolic group in an N-protecting group.

Mechanistic Study on Gold(I)-Catalyzed Unsaturated Spiroketalization Reaction

2022 ◽  
Vol 19 ◽  
Author(s):  
Kamlesh Sharma
Keyword(s):  
Activation Barrier ◽  
Ring Formation ◽  
Hydroxyl Group ◽  
Mechanistic Study ◽  
Protecting Group ◽  
Wide Range ◽  
Oxocarbenium Ion ◽  
Metal Catalyzed ◽  
Insight Into ◽  
Mechanism Of The Reaction

Abstract: The mechanism of metal-catalyzed spiroketalization of propargyl acetonide is explored by employing DFT with the B3LYP/6-31+G(d) method. Acetonide is used as a regioselective regulator in the formation of monounsaturated spiroketal. The energies of transition states, intermediates, reactants and products are calculated to provide new insight into the mechanism of the reaction. The energetic features, validation of the observed trends in regioselectivity are conferred in terms of electronic indices via FMO analysis. The presence of acetonide facilitates a stepwise spiroketalization as it masks the competing nucleophile, and thus hydroxyl group present, exclusively acts as a nucleophile. The vinyl gold intermediate 3 is formed from 2 via activation barrier TS1. This is the first ring formation, which is 6-exo-dig cyclization. The intermediate 3 is converted into allenyl ether 4, which isomerizes to the intermediate oxocarbenium ion 5 via activation barrier TS2. The intermediate 5 cyclizes to 6 via TS3. This is the second ring formation. The intermediate 6 on protodeauration turns into 6,6-monounsaturated spiroketal 7. It is concluded that acetonide as a protecting group serves the purpose, and thus a wide range of spiroketals can be prepared, regioselectivity.

Alkene Difunctionalization Directed by Free Amines: Diamine Synthesis via Nickel-Catalyzed 1,2-Carboamination

2021 ◽  
Author(s):  
Taeho Kang ◽  
José Manuel González ◽  
Zi-Qi Li ◽  
Klement Foo ◽  
Peter Cheng ◽  
...  
Keyword(s):  
Nickel Catalyst ◽  
Room Temperature ◽  
Kinetic Studies ◽  
Fine Tuning ◽  
Secondary Amines ◽  
Protecting Group ◽  
Wide Range ◽  
Leaving Group ◽  
Primary And Secondary Amines ◽  
Reaction Proceeds

A versatile method to access differentially substituted 1,3- and 1,4-diamines via a nickel-catalyzed three-component 1,2-carboamination of alkenyl amines with aryl/alkenylboronic ester nucleophiles and N–O electrophiles is reported. The reaction proceeds efficiently with free primary and secondary amines without needing a directing auxiliary or protecting group, and is enabled by fine-tuning the leaving group on the N–O reagent. The transformation is highly regioselective and compatible with a wide range of coupling partners and alkenyl amine substrates, all performed at room temperature. A series of kinetic studies support a mechanism in which alkene coordination to the nickel catalyst is turnover-limiting.

scholarly journals A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

2019 ◽  
Vol 15 ◽  
pp. 1523-1533 ◽  
Author(s):  
András György Németh ◽  
György Miklós Keserű ◽  
Péter Ábrányi-Balogh
Keyword(s):  
Elemental Sulfur ◽  
Building Blocks ◽  
Reaction Conditions ◽  
One Pot ◽  
Catalyst Free ◽  
Synthetic Procedure ◽  
Three Component Reaction ◽  
Wide Range ◽  
Organic Chemist ◽  
The One

A new multicomponent reaction has been developed between isocyanides, sulfur and alcohols or thiols under mild reaction conditions to afford O-thiocarbamates and dithiocarbamates in moderate to good yields. The one-pot reaction cascade involves the formation of an isothiocyanate intermediate, thus a catalyst-free synthesis of isothiocyanates, as valuable building blocks from isocyanides and sulfur is proposed, as well. The synthetic procedure suits the demand of a modern organic chemist, as it tolerates a wide range of functional groups, it is atom economic and easily scalable.

Catalyst-Free Synthesis of Diastereomerically Pure 3-Sulfonyl­azetidin-2-ones via Microwave-Assisted Tandem Wolff Rearrangement–Staudinger Cycloaddition

Synthesis ◽  
2020 ◽  
Author(s):  
Mikhail Krasavin ◽  
Judith Synofzik ◽  
Olga Bakulina ◽  
Olga Balabas ◽  
Dmitry Dar’in
Keyword(s):  
Drug Design ◽  
Single Crystal ◽  
Wolff Rearrangement ◽  
X Ray ◽  
Design And Optimization ◽  
X Ray Crystallography ◽  
Microwave Assisted ◽  
Catalyst Free ◽  
Relative Stereochemistry ◽  
Wide Range

A wide range of α-diazo-β-ketosulfones have been applied to thermally promoted tandem Wolff rearrangement – Staudinger [2+2] cycloaddition with imines to give polysubstituted β-lactam sulfones. Dia­stereomerically pure syn-diastereomers were obtained in good yields and the relative stereochemistry was confirmed by single-crystal X-ray crystallography. These findings significantly expand the scope of this transformation, in contrast to substantial limitations reported previously. Moreover, this methodology enables flexible exploration of new substitution patterns around the privileged β-lactam core for drug design and optimization.

scholarly journals Palladium-catalyzed α-arylation for the addition of small rings to aromatic compounds

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhi-Tao He ◽  
John F. Hartwig
Keyword(s):  
Electronic Properties ◽  
Aromatic Compounds ◽  
Ring Opening ◽  
Biologically Active ◽  
High Yield ◽  
Protecting Group ◽  
Mechanistic Studies ◽  
Claisen Condensation ◽  
Wide Range ◽  
Palladium Catalyzed

Abstract Small, strained rings have rigid, defined conformations and unique electronic properties. For these reasons, many groups seek to use these subunits to form biologically active molecules. We report a generally applicable approach to attach small rings to a wide range of aromatic compounds by palladium-catalyzed α-arylation of cyclopropyl, cyclobutyl and azetidinyl esters. The direct α-arylation of cyclopropyl esters and cyclobutyl esters is achieved in high yield by ensuring that the rate of coupling exceeds the rate of Claisen condensation. The α-arylation of azetidines is achieved without ring opening of the strained saturated heterocycle by conducting the reactions with an azetidine derivative bearing a benzyl protecting group on nitrogen. Mechanistic studies show that the α-arylation of small rings is challenging because of the weak acidity of α C-H bond (cyclopropanes), strong sensitivity of the strained esters to Claisen condensation (cyclobutatanes), or facile decomposition of the enolates (azetidinyl esters).

The pigmentation of the jellyfish, Pelagia noctiluca (Forskål) var. panopyra Péron & Lesueur

1954 ◽  
Vol 142 (908) ◽  
pp. 392-408 ◽  
Keyword(s):  
Amino Acids ◽  
Silver Nitrate ◽  
Absorption Maximum ◽  
Pelagia Noctiluca ◽  
Wide Range ◽  
Group A ◽  
Phenolic Group ◽  
Pass Through ◽  
Hydrolysis Of ◽  
Ammoniacal Silver

Four or more pigm ents, viz. at least two blue, a brown and a m agenta, have been found in Pelagia noctiluca var. panopyra . One blue occurs in the lips, a similar one in the exumbrella, and another in the gonadial endoderm and the gastric filaments. The brown occurs in the ectoderm of the exumbrella, in the gonads and the m esogloea; the m agenta occurs in the mesogloea. The blues are intracellular, the m agenta extracellular, and th e brown both intracellular and extracellular. The pigm entary material occurs either as m inute free ellipsoids or spheroids, or in association w ith larger colourless bodies. The extracted pigm ents show absorption m axim a as follows: blue from the gonads and gastric filaments, 632·5, 590 and 560 m μ ; blue from the exumbrella, 545 to 550 m μ , and that from the lips, 537 to 547 m μ ; magenta, 490 to 498 m μ . Autolysis and hydrolysis of the blue gonadial and of the magenta pigment by alkali or by trypsin, shifts the absorption maxima toward the shorter wave-lengths. The magenta pigment was studied in detail, and its solubility, its behaviour towards denaturants and its incapacity to pass through a collodion membrane, suggest that it is a chromoprotein. The chromogen, precipitated from tryptic digests by alkali, showed an absorption maximum at 380 m μ ; it was insoluble in a wide range of solvents, and could be oxidized and reduced only by relatively drastic means. It reduced ammoniacal silver nitrate in the dark. It was shown to contain chlorine, but no sulphur or phosphorus; it contains organically combined nitrogen, but no protein or α-amino-acids. Various tests showed the presence of a substituted phenolic group, a pyrrole group, and the indole nucleus. It thus appears to be a melanoid. No evidence was obtained for the existence of an active tyrosinase.

An atmosphere and light tuned highly diastereoselective synthesis of cyclobuta/penta[b]indoles from aniline-tethered alkylidenecyclopropanes with alkynes

2018 ◽  
Vol 54 (23) ◽  
pp. 2870-2873 ◽  
Author(s):  
Bo Cao ◽  
Yin Wei ◽  
Min Shi
Keyword(s):  
Indole Derivatives ◽  
Diastereoselective Synthesis ◽  
Free Atmosphere ◽  
Catalyst Free ◽  
Wide Range

A catalyst-free atmosphere and light tuned highly diastereoselective synthesis of cyclobuta/penta[b]indoles from aniline-tethered alkylidenecyclopropanes and alkynes was developed, which provided a wide range of cyclobuta- and cyclopenta[b]indole derivatives in good yields.

Michael Addition of Aryl Thiols to 3-(2,2,2-Trifluoroethylidene)Oxindoles under Catalyst-Free Conditions: The Rapid Synthesis of Sulfur-Containing Oxindole Derivatives

2018 ◽  
Vol 42 (4) ◽  
pp. 210-214
Author(s):  
Bo Chen ◽  
Jiaheng Lei ◽  
Junling Zhao
Keyword(s):  
Michael Addition ◽  
Room Temperature ◽  
Rapid Synthesis ◽  
Efficient Catalyst ◽  
Mild Conditions ◽  
Catalyst Free ◽  
Wide Range ◽  
High Yields ◽  
The Michael Addition ◽  
Sulfur Containing

A mild and efficient catalyst-free method for the rapid synthesis at room temperature of 3-thiomethylated oxindole derivatives has been achieved via the Michael addition of aryl thiols to ring and 1-substituted 3-(2,2,2-trifluoroethylidene)oxindoles in dichloromethane. The method was applicable to a wide range of thiols and variously substituted 3-(2,2,2-trifluoroethylidene)oxindoles under mild conditions as demonstrated by the synthesis in high yields with good diastereoselectivities of 30 3-thiomethylated oxindoles bearing a trifluoromethyl group.

Wide Range Photodetector Based on Catalyst Free Grown Indium Selenide Microwires

2014 ◽  
Vol 6 (12) ◽  
pp. 9550-9556 ◽  
Author(s):  
Zulfiqar Ali ◽  
Misbah Mirza ◽  
Chuanbao Cao ◽  
Faheem K. Butt ◽  
M. Tanveer ◽  
...  
Keyword(s):  
Indium Selenide ◽  
Catalyst Free ◽  
Wide Range

Catalyst-free iodine-mediated living radical polymerization under irradiation over a wide visible-light spectral scope

2016 ◽  
Vol 7 (21) ◽  
pp. 3576-3588 ◽  
Author(s):  
Xiaodong Liu ◽  
Lifen Zhang ◽  
Zhenping Cheng ◽  
Xiulin Zhu
Keyword(s):  
Visible Light ◽  
Radical Polymerization ◽  
Living Radical Polymerization ◽  
Led Light ◽  
Catalyst Free ◽  
Wide Range ◽  
Free Iodine ◽  
Methyl Methacrylates

Catalyst-free iodine-mediated photo-induced solution LRP of methyl methacrylates under LED light was successfully established over a wide range of irradiation wavelengths (390–630 nm).

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