The Azidosulfonylation of Terminal Alkynes Leading to β-azidovinyl Sulfones

2021 ◽  
Author(s):  
Long Zheng ◽  
Zhanjing Wang ◽  
Chen Li ◽  
Yong Wu ◽  
Zhaohong Liu ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Functional Group ◽  
High Yield ◽  
Terminal Alkynes

We reported herein the first example of N3 radical-mediated azidosulfonylation of alkynes, affording the β-azidovinyl sulfone products in broad substrate scope, excellent functional group compatibility, and high yield. DFT calculations...

Iridium-Catalyzed Silylation of C-H bonds in Unactivated Arenes: A Sterically-Encumbered Phenanthroline Ligand Accelerates Catalysis Enabling New Reactivity

2019 ◽  
Author(s):  
Caleb Karmel ◽  
Zhewei Chen ◽  
John Hartwig
Keyword(s):  
High Activity ◽  
Functional Group ◽  
Activity Analysis ◽  
High Reactivity ◽  
High Yield ◽  
Phen Ligand ◽  
Mechanistic Studies ◽  
Phenanthroline Ligand ◽  
First Time ◽  
New System

We report a new system for the silylation of aryl C-H bonds. The combination of [Ir(cod)(OMe)]<sub>2</sub> and 2,9-Me<sub>2</sub>-phenanthroline (2,9-Me<sub>2</sub>phen) catalyzes the silylation of arenes at lower temperatures and with faster rates than those reported previously, when the hydrogen byproduct is removed, and with high functional group tolerance and regioselectivity. Inhibition of reactions by the H<sub>2</sub> byproduct is shown to limit the silylation of aryl C-H bonds in the presence of the most active catalysts, thereby masking their high activity. Analysis of initial rates uncovered the high reactivity of the catalyst containing the sterically hindered 2,9-Me<sub>2</sub>phen ligand but accompanying rapid inhibition by hydrogen. With this catalyst, under a flow of nitrogen to remove hydrogen, electron-rich arenes, including those containing sensitive functional groups, undergo silylation in high yield for the first time, and arenes that underwent silylation with prior catalysts react over much shorter times with lower catalyst loadings. The synthetic value of this methodology is demonstrated by the preparation of key intermediates in the synthesis of medicinally important compounds in concise sequences comprising silylation and functionalization. Mechanistic studies demonstrate that the cleavage of the aryl C-H bond is reversible and that the higher rates observed with the 2,9-Me<sub>2</sub>phen ligand is due to a more thermodynamically favorable oxidative addition of aryl C-H bonds.

Yb(OTf)3-mediated regioselective hydroamination of ynamides with anilines or p-toluenesulfonamide

Synthesis ◽  
2021 ◽  
Author(s):  
Xiaobao Zeng ◽  
Qingyun Gu ◽  
Wenjing Dai ◽  
Yushan Xie ◽  
Xinyi Liu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Functional Group ◽  
High Yield ◽  
Diverse Range ◽  
Good Group ◽  
Rare Earth Salts

A rare-earth salts Yb(OTf)3-catalyzed regioselective hydroamination of ynamides with anilines or p-toluenesulfonamide has been developed. This protocol provided facile access to a diverse range of amidines with good group functional group tolerance in moderate to high yield.

scholarly journals Convenient synthesis of phosphinecarboxamide and phosphinecarbothioamide by hydrophosphination of isocyanates and isothiocyanates

2020 ◽  
Vol 56 (3) ◽  
pp. 443-445 ◽  
Author(s):  
Masumi Itazaki ◽  
Takanari Matsutani ◽  
Tomoya Nochida ◽  
Toshiyuki Moriuchi ◽  
Hiroshi Nakazawa
Keyword(s):  
Reaction Time ◽  
Functional Group ◽  
High Yield ◽  
Convenient Synthesis

Convenient synthesis of phosphinecarboxamidein by hydrophosphination of isocyanates (and isothiocyanates) was achieved without catalyst and solvent. This system shows shorter reaction time, high yield, and good functional group tolerance.

scholarly journals Homocoupling of terminal alkynes catalyzed by CuCl under solvent-free conditions

2021 ◽  
pp. 174751982110325
Author(s):  
Yan Xiao ◽  
Jiyu Gao ◽  
Peng Chen ◽  
Guangliang Chen ◽  
Zicheng Li ◽  
...  
Keyword(s):  
Functional Group ◽  
Reaction Times ◽  
Environmentally Friendly ◽  
Solvent Free ◽  
Copper Salt ◽  
Terminal Alkynes ◽  
Mild Conditions ◽  
Solvent Free Conditions ◽  
Environmentally Friendly Process

A series of symmetrical 1,4-disubstituted buta-1,3-diynes is prepared with excellent yields (up to 95%) through homocoupling of terminal alkynes catalyzed by a copper salt under solvent-free conditions. This method provides an environmentally friendly process to prepare 1,3-diynes in short reaction times under mild conditions. Furthermore, the method is suitable for a wide substrate scope and has excellent functional group compatibility. The reaction can also be scaled up to gram level.

scholarly journals Synthesis and Properties of 6-Aryl-4-azidocinnolines and 6-Aryl-4-(1,2,3-1H-triazol-1-yl)cinnolines

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2386 ◽  
Author(s):  
Natalia A. Danilkina ◽  
Nina S. Bukhtiiarova ◽  
Anastasia I. Govdi ◽  
Anna A. Vasileva ◽  
Andrey M. Rumyantsev ◽  
...  
Keyword(s):  
Photoinduced Electron Transfer ◽  
Functional Group ◽  
Click Reaction ◽  
Bromine Atom ◽  
Photophysical Properties ◽  
Triazole Ring ◽  
Synthetic Approach ◽  
Terminal Alkynes ◽  
Reaction Products ◽  
Fluorescent Properties

An efficient approach towards the synthesis of 6-aryl-4-azidocinnolines was developed with the aim of exploring the photophysical properties of 6-aryl-4-azidocinnolines and their click reaction products with alkynes, 6-aryl-4-(1,2,3-1H-triazol-1-yl)cinnolines. The synthetic route is based on the Richter-type cyclization of 2-ethynyl-4-aryltriazenes with the formation of 4-bromo-6-arylcinnolines and nucleophilic substitution of a bromine atom with an azide functional group. The developed synthetic approach is tolerant to variations of functional groups on the aryl moiety. The resulting azidocinnolines were found to be reactive in both CuAAC with terminal alkynes and SPAAC with diazacyclononyne, yielding 4-triazolylcinnolines. It was found that 4-azido-6-arylcinnolines possess weak fluorescent properties, while conversion of the azido function into a triazole ring led to complete fluorescence quenching. The lack of fluorescence in triazoles could be explained by the non-planar structure of triazolylcinnolines and a possible photoinduced electron transfer (PET) mechanism. Among the series of 4-triazolylcinnoline derivatives a compound bearing hydroxyalkyl substituent at triazole ring was found to be cytotoxic to HeLa cells.

NBS-promoted halosulfonylation of terminal alkynes: highly regio- and stereoselective synthesis of (E)-β-halo vinylsulfones

2014 ◽  
Vol 1 (4) ◽  
pp. 361-364 ◽  
Author(s):  
Yang Gao ◽  
Wanqing Wu ◽  
Yubing Huang ◽  
Kefan Huang ◽  
Huanfeng Jiang
Keyword(s):  
Stereoselective Synthesis ◽  
High Yield ◽  
Terminal Alkynes

An efficient NBS-promoted method for the synthesis of (E)-β-halo vinylsulfones with high yield and selectivity has been developed.

scholarly journals Selective Manganese-Catalyzed Dimerization and Cross-Coupling of Terminal Alkynes

2021 ◽  
Author(s):  
Stefan Weber ◽  
Luis F. Veiros ◽  
Karl Kirchner
Keyword(s):  
Dft Calculations ◽  
Precious Metal ◽  
Bond Cleavage ◽  
Cross Coupling ◽  
Metal Catalyst ◽  
Catalyst Loading ◽  
Terminal Alkynes ◽  
Migratory Insertion ◽  
Earth Abundant ◽  
First Time

<div>For the first time, an efficient manganese-catalyzed dimerization of terminal alkynes to afford 1,3-enynes is described. This reaction is atom economic, implementing an inexpensive, earth abundant non-precious metal catalyst. The pre-catalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate which undergoes rapid C-H bond cleavage of the alkyne forming an active Mn(I) acetylide catalyst [Mn(dippe)(CO)2(C≡CPh)(η2-HC≡CPh)] together with liberated butanal. A range of aromatic and aliphatic terminal alkynes were efficiently and selectively converted into head-to-head Z-1,3-enynes and head-to-tail gem-1,3-enynes, respectively, in good to excellent yields. Moreover, cross-coupling of aromatic and aliphatic alkynes yields selectively head-to-tail gem-1,3-enynes. In all cases, the reactions were performed at 70 °C with a catalyst loading of 1-2 mol %. A mechanism based on DFT calculations is presented.</div><div><br></div>

scholarly journals SYNTHESIS OF A 1,2,3-TRIAZOLE-CONTAINING MACROCYCLE BASED ON THE "CLICK CHEMISTRY" REACTION AND ANALYSIS OF ITS PLANAR CHIRALITY USING NMR AND DFT CALCULATIONS

2020 ◽  
pp. 55-61
Author(s):  
H. Yampolska ◽  
S. Kharchenko ◽  
A. Kozytskyi ◽  
A. Kyrylchuk ◽  
Z. Voitenko ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Click Chemistry ◽  
Protein Interactions ◽  
Variable Temperature ◽  
Triazole Ring ◽  
Building Blocks ◽  
Ring Closure ◽  
Amide Bond ◽  
High Yield ◽  
Planar Chirality

Macrocycles represent previously unexplored promising drug candidates, that can be useful for treating protein-protein interactions. Atropoisomerism is an inherent feature of the natural macrocyclic peptides that is significant for their activity and selectivity, and, therefore, should be introduced into newly synthesized macrocycles. Synthesis of the libraries of artificial macrocycles faces many challenges due to their structure and size. Herein we report on the preparation of a 16-membered macrocycle containing 1,2,3-triazole ring, spiro-piperidine, and phenyl moieties, as well as a chiral carbon atom. Our approach to the macrocycle was inspired by the "build/couple/pair" (B/C/P) strategy, a part of diversity-oriented synthesis methodology. We have employed readily accessible starting materials and robust synthetic procedures which allowed us to obtain the target macrocycle in a high yield. Standard methods of amide bond formation were used for the coupling of macrocycle building blocks. Click chemistry azide-alkyne cycloaddition was exploited at the final ring closure step. The assignment of signals in 1H and 13C NMR spectra of the macrocycle was performed using a series of 2D NMR techniques. The macrocycle displayed planar chirality, which, in a combination with a stereocenter with the known configuration, was sufficient to propose possible structures of diastereomers. The diastereomers could differ by the relative position of triazole ring. Their racemization could occur through a "rope skipping" motion involving the cyclic chain crossing the plane of 1,2,3-triazole ring. The supposed structures of diastereomers were corroborated by means of a various NMR spectroscopy techniques and DFT calculations. Analysis of the amide NH chemical shift temperature coefficients coupled with the data on optimized geometries obtained by DFT convincingly demonstrated that the intramolecular hydrogen bonds play a major role in stabilization of the diastereomer structures. According to the variable temperature NMR experiment, the interconversion of two diastereomers did not occur even at heating up to 70 °C.

scholarly journals One-Pot Synthesis of (Z)-β-Halovinyl Ketones via the Cascade of Sonogashira Coupling and Hydrohalogenation

2021 ◽  
Vol 8 ◽  
Author(s):  
Fa-Jie Chen ◽  
Zhenguo Hua ◽  
Jianhui Chen ◽  
Jiajia Chen ◽  
Daesung Lee ◽  
...  
Keyword(s):  
Efficient Method ◽  
Room Temperature ◽  
Copper Catalyst ◽  
High Yield ◽  
Sonogashira Coupling ◽  
Terminal Alkynes ◽  
Acid Chlorides ◽  
Triflic Acid ◽  
One Pot

Herein, we report an efficient method for the synthesis of (Z)-β-halovinyl ketones through a one-pot Sonogashira coupling and hydrohalogenation reaction promoted by palladium-copper catalyst and Brønsted acid. The ynone intermediates are generated in situ from readily available acid chlorides and terminal alkynes at room temperature, which are directly converted to (Z)-β-halovinyl ketones by treating with triflic acid. This method avoids the use of an external halogen source and features broad substrate scope, high yield, and good to excellent stereoselectivity.

scholarly journals Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids

2020 ◽  
Author(s):  
Zi-Qi Li ◽  
Yue Fu ◽  
Ruohan Deng ◽  
Van Tran ◽  
Yang Gao ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Transition State ◽  
Carboxylic Acids ◽  
Alkyl Group ◽  
Steric Effects ◽  
High Yield ◽  
Mechanistic Studies ◽  
Ligand Environment ◽  
Ligand Free ◽  
Electronic And Steric Effects

<div>A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99% yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state. <br></div>

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