scholarly journals Metal‐Free Regioselective Chloroazidation of Internal Alkynes

2018 ◽  
Author(s):  
Bin Huang ◽  
Raphael Liffert ◽  
Anthony Linden ◽  
Karl Gademann
Keyword(s):  
Metal Free ◽  
Internal Alkynes

K2S2O8-mediated metal-free direct P–H/C–H functionalization: a convenient route to benzo[b]phosphole oxides from unactivated alkynes

2016 ◽  
Vol 18 (12) ◽  
pp. 3522-3526 ◽  
Author(s):  
Dumei Ma ◽  
Weizhu Chen ◽  
Gaobo Hu ◽  
Yun Zhang ◽  
Yuxing Gao ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Metal Contamination ◽  
Heavy Metal Contamination ◽  
Radical Addition ◽  
Metal Free ◽  
Internal Alkynes ◽  
Convenient Route

A metal-free and K2S2O8-mediated radical addition/cyclization of internal alkynes leading to benzo[b]phosphole oxides was developed, which eliminates residual heavy metal contamination in the product.

Visible light promoted coupling of alkynyl bromides and Hantzsch esters for the synthesis of internal alkynes

2019 ◽  
Vol 17 (1) ◽  
pp. 181-185 ◽  
Author(s):  
Zhi-Yong Song ◽  
Chun-Lin Zhang ◽  
Song Ye
Keyword(s):  
Visible Light ◽  
Metal Free ◽  
Internal Alkynes

A metal-free visible light promoted synthesis of internal alkynes was developed via the C(sp3)–C(sp) coupling of alkynyl bromides and Hantzsch esters.

Metal-Free Cycloaddition of Internal Alkynes and Multifunctional Azides Under Solvent-Free Conditions

2014 ◽  
Vol 215 (17) ◽  
pp. 1603-1608 ◽  
Author(s):  
Benedict Sandmann ◽  
Bobby Happ ◽  
Jürgen Vitz ◽  
Renzo M. Paulus ◽  
Martin D. Hager ◽  
...  
Keyword(s):  
Solvent Free ◽  
Metal Free ◽  
Solvent Free Conditions ◽  
Internal Alkynes

Metal-Free Iodosulfonylation of Internal Alkynes: Stereodefined Access to Tetrasubstituted Olefins

2017 ◽  
Vol 359 (16) ◽  
pp. 2847-2856 ◽  
Author(s):  
Ravi Kumar ◽  
Vikas Dwivedi ◽  
Maddi Sridhar Reddy
Keyword(s):  
Metal Free ◽  
Internal Alkynes ◽  
Tetrasubstituted Olefins

Metal-free catalytic cascade to chromones: direct coupling of salicylaldehydes and activated alkynes triggered by aryloxyl radicals

RSC Advances ◽  
2015 ◽  
Vol 5 (129) ◽  
pp. 106350-106354 ◽  
Author(s):  
Ping Wang ◽  
Zhongfeng Li ◽  
Shengli Cao ◽  
Honghua Rao
Keyword(s):  
Addition Reaction ◽  
Direct Coupling ◽  
Metal Free ◽  
Internal Alkynes ◽  
One Step ◽  
Activated Alkynes

The first intermolecular addition reaction of aryloxyl radicals to CC bonds was disclosed, which can afford biologically important chromonsviaa PhNMe3I-catalyzed direct coupling of salicylaldehydes and activated internal alkynes in only one step.

An Expeditious Route for the Synthesis of Oxazepine Triazolo-β-Lactams through Intramolecular Metal-Free [3+2] Azide–Alkyne Cycloaddition

2020 ◽  
Vol 73 (7) ◽  
pp. 654
Author(s):  
Ram N. Yadav ◽  
Sunena Chandra ◽  
Armando Paniagua ◽  
Md. Firoj Hossain ◽  
Bimal Krishna Banik
Keyword(s):  
Sodium Azide ◽  
Good Yield ◽  
Cycloaddition Reaction ◽  
Present Approach ◽  
One Pot ◽  
Metal Free ◽  
Internal Alkynes

A copper-free intramolecular azide–alkyne cycloaddition reaction of 4-hydroxymethyl-β-lactam with sodium azide has been described. The present approach involves the incorporation of an alkyne moiety through O-alkynylation of 3-hydroxy β-lactam with various propargylic halides. The generality of the method has been demonstrated by treating the corresponding tosylates or mesylates of the hydroxymethyl functionality of a variety of β-lactam-tethered terminal and internal alkynes with sodium azide in a one-pot three-step reaction to furnish novel oxazepane-β-lactam fused triazole scaffolds of diverse interest in good yield.

Metal free carboamination of internal alkynes – an easy access to polysubstituted quinolines

2016 ◽  
Vol 52 (33) ◽  
pp. 5761-5764 ◽  
Author(s):  
T. Stopka ◽  
M. Niggemann
Keyword(s):  
Bond Formation ◽  
Acid Catalyst ◽  
Easy Access ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Metal Free ◽  
Brönsted Acid ◽  
Brønsted Acid Catalyst ◽  
Internal Alkynes ◽  
Brönsted Acid Catalyst

A synergistic Brønsted acid catalyst was used to intermolecularly generate vinyl cations for a C–C bond formation – Schmidt rearrangement – sequence.

scholarly journals Base-Promoted Annulation of Amidoximes with Alkynes: Simple Access to 2,4-Disubstituted Imidazoles

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3621
Author(s):  
Hina Mehmood ◽  
Muhammad Asif Iqbal ◽  
Le Lu ◽  
Ruimao Hua
Keyword(s):  
Transition Metal ◽  
Imidazole Ring ◽  
Terminal Alkynes ◽  
Synthetic Route ◽  
Metal Free ◽  
Ligand Free ◽  
Internal Alkynes ◽  
Efficient Construction

An efficient construction of imidazole ring by a Cs2CO3-promoted annulation of amidoximes with terminal alkynes in DMSO has been developed. This protocol provides a simple synthetic route with high atom-utilization for the synthesis of 2,4-disubstituted imidazoles in good yields under transition-metal-free and ligand-free conditions. Internal alkynes can also undergo the annulation to give 2,4,5-trisubstituted imidazoles.

The Shadow Widths of Very Small Particles are Formed Independently of the Metal Cap Build Up on the Particle

1981 ◽  
Vol 39 ◽  
pp. 568-569
Author(s):  
George C. Ruben
Keyword(s):  
Gold Particle ◽  
Film Surface ◽  
Small Particles ◽  
Geometric Process ◽  
Metal Free ◽  
Shadow Area

The formation of shadows behind small particles has been thought to be a geometric process (GP) where the metal cap build up on the particle creates a shadow width the same size as or larger than the particle. This GP cannot explain why gold particle shadow widths are generally larger than the gold particle and may have no appreciable metal cap build up (fig. 1). Ruben and Telford have suggested that particle shadow widths are formed by the width dependent deflection of shadow metal (SM) lateral to and infront of the particle. The trajectory of the deflected SM is determined by the incoming shadow angle (45°). Since there can be up to 1.4 times (at 45°) more SM directly striking the particle than the film surface, a ridge of metal nuclei lateral to and infront of the particle can be formed. This ridge in turn can prevent some SM from directly landing in the metal free shadow area. However, the SM that does land in the shadow area (not blocked by the particle or its ridge) does not stick and apparently surface migrates into the SM film behind the particle.

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