1,6-Addition of 1,2,3-NH triazoles to para-quinone methides: Facile access to highly selective N1 and N2 substituted triazoles

2022 ◽  
Author(s):  
Vishakha Rai ◽  
Kavyashree P. ◽  
Sarvesh S. Harmalkar ◽  
Sundar N. Dhuri ◽  
Mahagundappa R. Maddani
Keyword(s):  
Quinone Methides ◽  
Reaction Conditions

Regioselective syntheses of N1 and N2 substituted triazoles via 1,6-addition of 1,2,3-NH triazole with p-QM were developed under mild reaction conditions. Isomerization of N1 to N2 substituted triazoles was also achieved in the presence of AlCl3.

scholarly journals Diastereoselective synthesis of CF3-dihydrobenzofurans by [4+1] annulation of in situ-generated CF3-o-quinone methides and sulfur ylides

RSC Advances ◽  
2020 ◽  
Vol 10 (63) ◽  
pp. 38588-38591
Author(s):  
Babli K. Jha ◽  
Jaggaraju Prudhviraj ◽  
Prathama S. Mainkar ◽  
Nagender Punna ◽  
Srivari Chandrasekhar
Keyword(s):  
Diastereoselective Synthesis ◽  
Quinone Methides ◽  
Reaction Conditions ◽  
Sulfur Ylides

The first [4 + 1] annulation reaction of in situ-generated highly electrophilic CF3-ortho-quinone methides with sulphur ylides has been put forth under mild reaction conditions to access CF3-dihydrobenzofurans.

Synthesis of 4-(6H-dibenzo[b,e]thiepin-11-ylidene)cyclohexa-2,5-dienone and 4-(6H-dibenzo[b,e]oxepin-11-ylidene)cyclohexa-2,5-dienone

2002 ◽  
Vol 2002 (10) ◽  
pp. 516-517 ◽  
Author(s):  
Michael R. Jorgensen ◽  
Cedric W. McCleland ◽  
Benjamin Taljaard ◽  
Jana H. Taljaard
Keyword(s):  
Quinone Methides ◽  
Reaction Conditions

The synthesis of two novel quinone methides (4a and 4b) containing tricyclic heterocyclic systems with 7-membered central rings has been achieved in good yields under relatively mild reaction conditions.

DBU-Promoted Formal [4+2] Annulation Reactions of o-Chloromethyl Anilines with Azlactones

Synthesis ◽  
2020 ◽  
Author(s):  
Jianfeng Xu ◽  
Haojie Ji ◽  
Chonglong He ◽  
Hongjie Gao ◽  
Weijun Fu
Keyword(s):  
Protecting Groups ◽  
Synthetic Approach ◽  
Quinone Methides ◽  
Reaction Conditions ◽  
Salient Features

AbstractAn efficient 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-mediated formal [4+2] annulation reaction of aza-ortho-quinone methides (aza-oQMs) (generated from o-chloromethyl anilines) with enolates (formed from azlactones) is disclosed, delivering biologically significant 3,4-dihydroquinolin-2(1H)-one derivatives in moderate to good yields. The salient features of this reaction include readily accessible starting materials, broad substrate scope, mild reaction conditions, removable protecting groups, and a scalable synthetic approach.

An Efficient One-Pot Protocol for Direct Access to Diarylmethyl Thioglycosides with para-Quinone Methides via S-Glycosyl Isothiouronium Salts

Synlett ◽  
2020 ◽  
Vol 31 (17) ◽  
pp. 1713-1719
Author(s):  
Pintu Kumar Mandal ◽  
Atul Dubey
Keyword(s):  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Quinone Methide ◽  
Direct Access ◽  
Quinone Methides ◽  
Reaction Conditions ◽  
One Pot ◽  
Direct Preparation ◽  
The One ◽  
Rapid Conversion

An efficient one-pot protocol has been developed for the direct preparation of diarylmethyl thioglycosides starting from per-O-acetylated sugars via glycosyl isothiouronium salts. The one-pot reaction conditions involve rapid conversion of the per-O-acetylated sugar with thiourea in the presence of boron trifluoride etherate as catalyst to give the corresponding glycosyl isothiouronium salt, which is subsequently treated with a para-quinone methide in the presence of a base to give the a diarylmethyl thioglycoside in excellent yield.

scholarly journals Chiral Brønsted acid-catalyzed Friedel–Crafts alkylation of electron-rich arenes with in situ-generated ortho-quinone methides: highly enantioselective synthesis of diarylindolylmethanes and triarylmethanes

2015 ◽  
Vol 51 (8) ◽  
pp. 1461-1464 ◽  
Author(s):  
Satyajit Saha ◽  
Santosh Kumar Alamsetti ◽  
Christoph Schneider
Keyword(s):  
Enantioselective Synthesis ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Quinone Methides ◽  
Reaction Conditions ◽  
Brönsted Acid ◽  
Acid Catalyzed ◽  
Chiral Bronsted Acid ◽  
Hydrogen Bonded

Hydrogen-bonded, in situ-generated ortho-quinone methides undergo highly enantioselective Friedel–Crafts reactions with indoles and naphthols under mild reaction conditions.

scholarly journals Copper-catalyzed silylation of p-quinone methides: new entry to dibenzylic silanes

2015 ◽  
Vol 51 (100) ◽  
pp. 17684-17687 ◽  
Author(s):  
Aurora López ◽  
Alejandro Parra ◽  
Carlos Jarava-Barrera ◽  
Mariola Tortosa
Keyword(s):  
Quinone Methides ◽  
Reaction Conditions ◽  
High Yields ◽  
New Entry

An efficient and general copper(i)-catalyzed silylation of p-quinone-methides is described. Non-symmetric dibenzylic silanes are obtained in high yields under mild reaction conditions. These compounds can be used as bench-stable benzylic carbanion precursors.

scholarly journals Facile Synthesis of 2H-Benzo[h]Chromenes via an Arylamine-Catalyzed Mannich Cyclization Cascade Reaction

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3617
Author(s):  
Yueteng Zhang ◽  
Peng Ji ◽  
Xiang Meng ◽  
Feng Gao ◽  
Fanxun Zeng ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
High Efficiency ◽  
Cascade Reaction ◽  
Facile Synthesis ◽  
Quinone Methides ◽  
Reaction Conditions ◽  
Notable Feature ◽  
Efficient Generation ◽  
Mannich Cyclization

A simple arylamine-catalyzed Mannich-cyclization cascade reaction was developed for facile synthesis of substituted 2H-benzo[h]chromenes. The notable feature of the process included the efficient generation of ortho-quinone methides (o-QMs) catalyzed by a simple aniline. The mild reaction conditions allowed for a broad spectrum of 1- and 2-naphthols and trans-cinnamaldehydes to engage in the cascade sequence with high efficiency.

Undecagold labeling of tRNA

1991 ◽  
Vol 49 ◽  
pp. 44-45
Author(s):  
James F. Hainfeld ◽  
Kyra M. Alford ◽  
Mathias Sprinzl ◽  
Valsan Mandiyan ◽  
Santa J. Tumminia ◽  
...  
Keyword(s):  
High Resolution ◽  
Transmission Electron Micrograph ◽  
Anticodon Loop ◽  
Electron Micrograph ◽  
Reaction Conditions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The undecagold (Au11) cluster was used to covalently label tRNA molecules at two specific ribonucleotides, one at position 75, and one at position 32 near the anticodon loop. Two different Au11 derivatives were used, one with a monomaleimide and one with a monoiodacetamide to effect efficient reactions.The first tRNA labeled was yeast tRNAphe which had a 2-thiocytidine (s2C) enzymatically introduced at position 75. This was found to react with the iodoacetamide-Aun derivative (Fig. 1) but not the maleimide-Aun (Fig. 2). Reaction conditions were 37° for 16 hours. Addition of dimethylformamide (DMF) up to 70% made no improvement in the labeling yield. A high resolution scanning transmission electron micrograph (STEM) taken using the darkfield elastically scattered electrons is shown in Fig. 3.

Dimensionally-Controlled Hydrothermal Tm3+-doped Oxidic Nanocrystals and Their Photoluminescence Properties

2010 ◽  
Vol 1247 ◽  
Author(s):  
Rocío Calderón-Villajos ◽  
Carlos Zaldo ◽  
Concepción Cascales
Keyword(s):  
Single Crystals ◽  
Fluorescence Lifetimes ◽  
Photoluminescence Properties ◽  
Reaction Conditions ◽  
Hydrothermal Processes ◽  
Bulk Single Crystals ◽  
Template Free ◽  
Reaction Media

AbstractControlled reaction conditions in simple, template-free hydrothermal processes yield Tm-Lu2O3 and Tm-GdVO4 nanocrystals with well-defined specific morphologies and sizes. In both oxide families, nanocrystals prepared at pH 7 reaction media exhibit photoluminescence in ∼1.95 μm similar to bulk single crystals. For the lowest Tm3+ concentration (0.2 % mol) in GdVO4 measured 3H4 and 3F4 fluorescence lifetimes τ are very near to τrad.

Urea-Catalyzed Functionalization of Unactivated C–H Bonds

2020 ◽  
Author(s):  
Alex L. Bagdasarian ◽  
Stasik Popov ◽  
Benjamin Wigman ◽  
Wenjing Wei ◽  
woojin lee ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Organic Synthesis ◽  
High Energy ◽  
Acid Catalysts ◽  
Potential Utility ◽  
New Paradigm ◽  
Lewis Acid Catalysts ◽  
Reaction Conditions ◽  
Highly Active ◽  
Acidic Nature

Herein we report the 3,5bistrifluoromethylphenyl urea-catalyzed functionalization of unactivated C–H bonds. In this system, the urea catalyst mediates the formation of high-energy vinyl carbocations that undergo facile C–H insertion and Friedel–Crafts reactions. We introduce a new paradigm for these privileged scaffolds where the combination of hydrogen bonding motifs and strong bases affords highly active Lewis acid catalysts capable of ionizing strong C–O bonds. Despite the highly Lewis acidic nature of these catalysts that enables triflate abstraction from sp<sup>2</sup> carbons, these newly found reaction conditions allow for the formation of heterocycles and tolerate highly Lewis basic heteroaromatic substrates. This strategy showcases the potential utility of dicoordinated vinyl carbocations in organic synthesis.<br>

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