scholarly journals Base-Catalyzed Synthesis of Flavones via Thiol-Assisted Sequential Demethylation/Cyclization of 1-(2-methoxyphenyl)prop-2-yn-1-ones

2021 ◽  
Author(s):  
Ritiele Heck ◽  
Thiago Anjos ◽  
Maira R Giehl ◽  
Ricardo F Schumacher ◽  
Benhur Godoi
Keyword(s):  
Reaction Time ◽  
Secondary Metabolites ◽  
Transition Metal ◽  
Intramolecular Cyclization ◽  
Important Class ◽  
Short Reaction Time ◽  
Metal Free ◽  
Synthetic Strategy ◽  
Pharmacologically Active ◽  
Active Substances

Flavone and analogues represent an important class of biologically and pharmacologically active substances commonly found in the composition of diverse plants as part of the class of secondary metabolites. Herein, we have demonstrated an efficient and regioselective synthetic strategy for the preparation of functionalized flavones through sequential demethylation/6-endo-dig intramolecular cyclization of propyn-1-ones, using catalytic amounts of base in the presence of a thiol, by employing NMP as the solvent. The reactions proceeded smoothly under transition-metal-free and open to air conditions, furnishing the desired six-membered heterocycles in moderate to excellent yields, in short reaction time.

Iodine-mediated C–N and C–S bond formation: regioselective synthesis of benzo[4,5]imidazo[2,1-b]thiazoles

2017 ◽  
Vol 41 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Sethurajan Ambethkar ◽  
Muthalu Vellimalai ◽  
Vediappen Padmini ◽  
Nattamai Bhuvanesh
Keyword(s):  
Reaction Time ◽  
Intramolecular Cyclization ◽  
Simple Procedure ◽  
Bond Formation ◽  
Molecular Iodine ◽  
Regioselective Synthesis ◽  
Thiazole Derivatives ◽  
Short Reaction Time ◽  
Metal Free

The regioselective synthesis of benzo[4,5]imidazo[2,1-b]thiazole derivatives via amination (C–N) and intramolecular cyclization (C–S) reactions in the presence of molecular iodine has been reported. This method is base and metal free and features inexpensive catalysts, with a simple procedure and a short reaction time.

scholarly journals Metal-free formal synthesis of phenoxazine

2018 ◽  
Vol 14 ◽  
pp. 1491-1497 ◽  
Author(s):  
Gabriella Kervefors ◽  
Antonia Becker ◽  
Chandan Dey ◽  
Berit Olofsson
Keyword(s):  
Reaction Time ◽  
Transition Metal ◽  
Formal Synthesis ◽  
Metal Free ◽  
Diaryl Ether ◽  
Diaryliodonium Salt ◽  
Moderate Yield ◽  
Stable Iodine

A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O-arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho-disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time.

A Convenient Synthesis of 1,5-Fused 1,2,4-Triazoles from N-Arylamidines via Chloramine-T Mediated Intramolecular Oxidative N–N Bond Formation

Synthesis ◽  
2019 ◽  
Vol 51 (20) ◽  
pp. 3883-3890
Author(s):  
Ashish Bhatt ◽  
Rajesh K. Singh ◽  
Ravi Kant ◽  
Bhupendra K. Sarma
Keyword(s):  
Reaction Time ◽  
Bond Formation ◽  
Available N ◽  
Short Reaction Time ◽  
Metal Free ◽  
Convenient Synthesis ◽  
Chloramine T ◽  
High Yields ◽  
Short Time

A convenient synthesis of 1,5-fused 1,2,4-triazoles from readily available N-arylamidines is reported. The reaction is efficiently promoted by chloramine-T to afford the desired products mostly in high yields and in relatively short time, through direct metal-free oxidative N−N bond formation. The mild nature of the synthesis and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities.

Access to Furo[2,3‐ b ]pyridines by Transition‐Metal‐Free Intramolecular Cyclization of C3‐substituted Pyridine N ‐oxides

2018 ◽  
Vol 7 (5) ◽  
pp. 879-882 ◽  
Author(s):  
Dong Wang ◽  
Meng Shen ◽  
Yuxi Wang ◽  
Jianyong Hu ◽  
Junjie Zhao ◽  
...  
Keyword(s):  
Transition Metal ◽  
Intramolecular Cyclization ◽  
Metal Free

scholarly journals Et3N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

2020 ◽  
Vol 16 ◽  
pp. 1740-1753 ◽  
Author(s):  
Dharmender Singh ◽  
Vipin Kumar ◽  
Virender Singh
Keyword(s):  
Transition Metal ◽  
Elemental Sulfur ◽  
Photophysical Properties ◽  
Quantum Yields ◽  
One Pot ◽  
Light Emitting ◽  
Metal Free ◽  
One Pot Synthesis ◽  
Synthetic Strategy ◽  
Reaction Proceeds

A robust transition-metal-free strategy is presented to access novel β-carboline-tethered benzothiophenone derivatives from 1(3)-formyl-β-carbolines using elemental sulfur activated by Et3N/DMSO. This expeditious catalyst-free reaction proceeds through the formation of β-carboline-based 2-nitrochalcones followed by an incorporation of sulfur to generate multifunctional β-carboline-linked benzothiophenones in good to excellent yields. The synthetic strategy could also be extended towards the synthesis of β-carboline-linked benzothiophenes. Moreover, the afforded products emerged as promising fluorophores and displayed excellent light-emitting properties with quantum yields (ΦF) up to 47%.

A cascade process for the synthesis of ortho-formyl allyl aryl ethers and 2H-chromen-2-ol derivatives from arynes via trapping of o-quinone methide with an activated alkene

2019 ◽  
Vol 17 (2) ◽  
pp. 333-346 ◽  
Author(s):  
Abhilash Sharma ◽  
Pranjal Gogoi
Keyword(s):  
Transition Metal ◽  
Direct Synthesis ◽  
Quinone Methide ◽  
Cascade Process ◽  
Metal Free ◽  
Synthetic Strategy ◽  
Aryl Ethers ◽  
Three Component Coupling

A transition-metal free synthetic strategy for the direct synthesis of ortho-formyl substituted allyl aryl ethers and 2H-chromen-2-ol derivatives via a cascade three-component coupling of arynes, activated alkene and N,N-dimethylformamide.

Synthesis of Imidazo[1,5-a]quinolines via Metal-Free Oxidative Amination of sp3 C–H Bonds

Synthesis ◽  
2018 ◽  
Vol 50 (14) ◽  
pp. 2761-2767 ◽  
Author(s):  
Chen Ma ◽  
Huanhuan Liu ◽  
Xinfeng Wang
Keyword(s):  
Amino Acids ◽  
Transition Metal ◽  
Intramolecular Cyclization ◽  
Efficient Synthesis ◽  
Oxidative Amination ◽  
Metal Free ◽  
Oxidation System

A novel oxidative amination of sp3 C–H bonds was developed for the efficient synthesis of imidazo[1,5-a]quinolines from readily available α-amino acids and (2-azaaryl)methanes. This domino protocol, which was established in a TBAI-TBHP oxidation system, includes transition-metal-free decarboxylation and intramolecular cyclization. This method represented a new avenue for the synthesis of N-heterocycles using 2-methylquinolines as the synthon of quinoline-2-carbaldehydes.

Synthesis of 6-substituted indoloquinazolinones from arynes and 2-acyl-4-quinazolinones: a transition-metal free C–N and C–C bond formation strategy

2020 ◽  
Vol 44 (41) ◽  
pp. 17938-17953
Author(s):  
Abhilash Sharma ◽  
Pranjal Gogoi
Keyword(s):  
Transition Metal ◽  
Direct Synthesis ◽  
Bond Formation ◽  
Reaction Vessel ◽  
Metal Free ◽  
Synthetic Strategy ◽  
Single Reaction

A versatile transition-metal free synthetic strategy has been developed for the direct synthesis of 6-substituted indoloquinazolinones from 2-acyl-4-quinazolinones and aryne precursors. This cascade strategy proceeds via successive C–N and C–C bond formation in a single reaction vessel.

Transition-metal free C(sp2)–C(sp2) bond formation: arylation of 4-aminocoumarins using arynes as an aryl source

2019 ◽  
Vol 17 (40) ◽  
pp. 9014-9025 ◽  
Author(s):  
Abhilash Sharma ◽  
Pranjal Gogoi
Keyword(s):  
Transition Metal ◽  
Bond Formation ◽  
Single Step ◽  
Metal Catalyst ◽  
Metal Free ◽  
Synthetic Strategy

A mild, efficient and transition-metal free synthetic strategy has been developed for the α-arylation of 4-aminocoumarins using arynes as an aryl source. This synthetic strategy proceeds via C(sp2)–C(sp2) bond formation between 4-aminocoumarins and aryne precursors in a single step in the absence of a metal-catalyst.

Aryne insertion into the PO bond: one-pot synthesis of quaternary phosphonium triflates

2019 ◽  
Vol 17 (26) ◽  
pp. 6450-6460 ◽  
Author(s):  
Kashmiri Neog ◽  
Dhiraj Dutta ◽  
Babulal Das ◽  
Pranjal Gogoi
Keyword(s):  
Transition Metal ◽  
Phosphine Oxide ◽  
Direct Synthesis ◽  
One Pot ◽  
Metal Free ◽  
One Pot Synthesis ◽  
Synthetic Strategy

A novel transition-metal free synthetic strategy for the direct synthesis of quaternary phosphonium triflates via insertion of aryne into phosphine oxide.

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