scholarly journals TfOH mediated intermolecular electrocyclization for the synthesis of pyrazolines and its application in alkaloid synthesis

RSC Advances ◽  
2018 ◽  
Vol 8 (53) ◽  
pp. 30071-30075 ◽  
Author(s):  
Sesuraj Babiola Annes ◽  
Pothiappan Vairaprakash ◽  
Subburethinam Ramesh
Keyword(s):  
Synthetic Methodology ◽  
Metal Free ◽  
Alkaloid Synthesis ◽  
Synthetic Application

A metal free and green synthetic methodology employing aldehydes, phenylhydrazine and styrene mediated by TfOH has been developed to access 1,3,5-trisubstituted pyrazolines. The synthetic application of the methodology is demonstrated in the synthesis of a pyrazoline alkaloid.

Synthesis of Pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by Alkyne-Carbonyl Metathesis

Synthesis ◽  
2020 ◽  
Author(s):  
Peter Ehlers ◽  
Peter Langer ◽  
Marian Blanco Ponce ◽  
Silvio Parpart ◽  
Alexander Villinger ◽  
...  
Keyword(s):  
Heterocyclic Compounds ◽  
Metathesis Reaction ◽  
Synthetic Methodology ◽  
Facile Synthesis ◽  
Reaction Conditions ◽  
One Pot ◽  
Metal Free ◽  
Modular Synthesis

AbstractA concise and modular synthesis of pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by a one-pot two-step reaction consisting of electrophilic acylation followed by an alkyne-carbonyl-metathesis reaction as the final cyclization step is reported. This developed synthetic methodology allows the facile synthesis of these heterocyclic core structures in mainly high overall yields under metal-free conditions. Reaction conditions are carefully optimized and display a novel supplement to access these tricyclic heterocyclic compounds.

scholarly journals Transition-Metal-Free [3+2] Dehydration Cycloaddition of Donor-Acceptor Cyclopropanes With 2-Naphthols

2021 ◽  
Vol 9 ◽  
Author(s):  
Hua Zhao ◽  
Peng Shen ◽  
Dongru Sun ◽  
Hongbin Zhai ◽  
Yufen Zhao
Keyword(s):  
Transition Metal ◽  
Ring Opening ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Cyclization Reaction ◽  
Metal Free ◽  
Efficient Access ◽  
Donor Acceptor ◽  
Acid Catalyzed ◽  
Synthetic Application

A Brønsted acid-catalyzed domino ring-opening cyclization transformation of donor-acceptor (D-A) cyclopropanes and 2-naphthols has been developed. This formal [3+2] cyclization reaction provided novel and efficient access to the naphthalene-fused cyclopentanes in the absence of any transition-metal catalysts or additives. This robust procedure was completed smoothly on a gram-scale to afford the corresponding product with comparable efficiency. Furthermore, the synthetic application of the prepared product has been demonstrated by its transformation into a variety of synthetically useful molecules.

Rearrangement Reactions in Aza-Vinylogous Povarov Products: Metal-Free Synthesis of C3 -Functionalized Quinolines and Studies on their Synthetic Application

2019 ◽  
Vol 2019 (38) ◽  
pp. 6452-6464 ◽  
Author(s):  
José Clerigué ◽  
Giulia Bianchini ◽  
Pascual Ribelles ◽  
Tomás Tejero ◽  
Pedro Merino ◽  
...  
Keyword(s):  
Metal Free ◽  
Rearrangement Reactions ◽  
Synthetic Application

scholarly journals Recent progress in reactivity study and synthetic application of N-heterocyclic phosphorus hydrides

2020 ◽  
Author(s):  
Jingjing Zhang ◽  
Jin-Dong Yang ◽  
Jin-Pei Cheng
Keyword(s):  
Recent Progress ◽  
Catalytic Reduction ◽  
Lone Pair ◽  
Metal Free ◽  
Practical Information ◽  
Reactivity Study ◽  
Lone Pair Electrons ◽  
Synthetic Application

Abstract N-heterocyclic phosphines (NHPs) have recently emerged as a new group of promising catalysts for metal-free reductions, owing to their unique hydridic reactivity. The excellent hydricity of NHPs, which rivals or even exceeds those of many metal-based hydrides, is the result of hyperconjugative interactions between the lone-pair electrons on N atoms and the adjacent σ*(P–H) orbital. Compared with the conventional protic reactivity of phosphines, this umpolung P–H reactivity leads to hydridic selectivity in NHP-mediated reductions. This reactivity has therefore found many applications in the catalytic reduction of polar unsaturated bonds and in the hydroboration of pyridines. This review summarizes recent progress in studies of the reactivity and synthetic applications of these phosphorus-based hydrides, with the aim of providing practical information to enable exploitation of their synthetically useful chemistry.

scholarly journals Visible Light Promoted Metal Free Sustainable Reduction of Activated Carbon-Carbon Double Bonds Without Any External Reductant

2021 ◽  
Author(s):  
Anindita Bhowmick ◽  
Prakash K. Warghude ◽  
Dr. Ramakrishna G. Bhat
Keyword(s):  
Double Bond ◽  
Visible Light ◽  
Eosin Y ◽  
Mechanistic Studies ◽  
Double Bonds ◽  
Efficient Catalyst ◽  
Metal Free ◽  
Effective Reduction ◽  
Synthetic Application

Visible light promoted chemo-selective metal free hydrogenation of activated double bond has been achieved via photoredox catalysis. Eosin Y has proved to an efficient catalyst for the effective reduction of C-C double bonds of isatins, oxindoles and maleimides under visible light. The method worked efficiently without the aid of any external reductants. Commercially viable DIPEA has been employed as a sacrificial electron donor and it’s in-situ generated cationic radical acts as reductant in this transformation. The method proved to be practical as a broad range of substrates containing activated double bond were easily reduced. The method proved to be scalable on a gram scale and the reduced product has been utilized successfully for the further synthetic application. The systematic and detailed mechanistic studies reveal the reductive quenching of the photocatalyst by the activated double bond.

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.

Recent advancement in the electrocatalytic synthesis of ammonia

Nanoscale ◽  
2020 ◽  
Vol 12 (15) ◽  
pp. 8065-8094 ◽  
Author(s):  
Xudong Wen ◽  
Jingqi Guan
Keyword(s):  
Metal Oxide ◽  
Oxide Catalysts ◽  
Single Atom ◽  
Metal Oxide Catalysts ◽  
Metal Free ◽  
Recent Advancement ◽  
Nanocomposite Catalysts

Different kinds of electrocatalysts used in NRR electrocatalysis (including single atom catalysts, metal oxide catalysts, nanocomposite catalysts, and metal free catalysts) are introduced.

Transition-metal-free catalytic hydroboration reduction of amides to amines

2020 ◽  
Vol 7 (21) ◽  
pp. 3515-3520
Author(s):  
Wubing Yao ◽  
Jiali Wang ◽  
Aiguo Zhong ◽  
Shiliang Wang ◽  
Yinlin Shao
Keyword(s):  
Transition Metal ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Value Added ◽  
Metal Free

The selective catalytic reduction of amides to value-added amine products is a desirable but challenging transformation.

Deaminative carbonylative thioesterification of activated alkylamines with thiophenols under transition-metal-free conditions

2021 ◽  
Author(s):  
Fengqian Zhao ◽  
Xiao-Feng Wu
Keyword(s):  
Free Radical ◽  
Transition Metal ◽  
Metal Free

A transition-metal-free radical carbonylation of activated alkylamines with thiophenols has been successfully developed. Various thioesters were selectively produced with moderate to good yields.

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