scholarly journals 2-Arylhydrazonopropanals as Building Blocks in Heterocyclic Chemistry: Microwave Assisted Condensation of 2-Arylhydrazonopropanals with Amines and Active Methylene Reagents

Molecules ◽  
2003 ◽  
Vol 8 (12) ◽  
pp. 910-923 ◽  
Author(s):  
Khadijah Al-Zaydi ◽  
Rita Borik ◽  
Mohamed Elnagdi
Keyword(s):  
Building Blocks ◽  
Heterocyclic Chemistry ◽  
Microwave Assisted ◽  
Active Methylene

Regioselective Synthesis of Potent 4,5,6,7-Tetrahydroindazole Derivatives via Microwave-assisted Vilsmeier-Haack Reaction and their Antioxidant Activity Evaluation

2019 ◽  
Vol 16 (3) ◽  
pp. 194-201 ◽  
Author(s):  
Renu Bala ◽  
Vandana Devi ◽  
Pratibha Singh ◽  
Navjot Kaur ◽  
Pawandeep Kaur ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Microwave Irradiation ◽  
Biological Activities ◽  
Reaction Times ◽  
Conventional Heating ◽  
High Chemical ◽  
Microwave Assisted ◽  
Work Up ◽  
Active Methylene ◽  
By Products

Background: Tetrahydroindazole, a member of the fused-pyrazole system, is a least studied class of heterocyclic compounds owing to its scarcity in nature. However, a large number of synthetically prepared tetrahydroindazoles are known to show a variety of biological activities such as interleukin- 2 inducible T-Cell kinase inhibitors, AMPA receptor positive allosteric modulators, antitumor, antituberculosis, anti-inflammatory and antimicrobial activities. Vilsmeier-Haack reaction is one of the most important chemical reactions used for formylation of electron rich arenes. Even though Vilsmeier- Haack reaction was studied on a wide variety of hydrazones derived from active methylene compounds, literature lacks the examples of the use of 4-substituted cyclohexanones as a substrate for the synthesis of 4,5,6,7-tetrahydroindazoles. The study of the reaction of Vilsmeier-Haack reagent with hydrazones derived from cyclic keto compounds having active methylene has been considered the interested topic of investigation. In the present study, ethyl cyclohexanone-4-carboxylate was treated with one equivalent of various hydrazines for two hours and the resulted hydrazones were further treated with an OPC-VH reagent (Vilsmeier-Haack reagent isolated from phthaloyl dichloride and N,Ndimethylformamide) afforded 4,5,6,7-tetrahydroindazoles in excellent yields. The synthesized compounds 4a-f and 5a-f were screened for their antioxidant activities using the DPPH radical scavenging assay. The target compounds were synthesized regioselectively using 4+1 approach in excellent yields. A number of experiments using both conventional heating as well as microwave irradiation methods were tried and on comparison, microwave irradiation method was found excellent in terms of easy work up, high chemical yields, shortened reaction times, clean and, no by-products formation. Some of the synthesized compounds showed significant antioxidant activity. The microwave assisted synthesis of 4,5,6,7-tetrahydroindazoles from ethyl cyclohexanone-4-carboxylate has been reported under mild conditions in excellent yield. Easy work up, high chemical yield, shortened reaction times, clean and no by-products formation are the major advantages of this protocol. These advantages may make this method useful for chemists who are interested in developing novel 4,5,6,7-tetrahydroindazole based drugs.

Contribution to PNA-RNA Chimera Synthesis: One-Pot Microwave-Assisted Ugi Reaction to Obtain Dimeric Building Blocks

2016 ◽  
Vol 2017 (3) ◽  
pp. 469-475 ◽  
Author(s):  
Reuben Ovadia ◽  
Clémence Mondielli ◽  
Jean-Jacques Vasseur ◽  
Carine Baraguey ◽  
Karine Alvarez
Keyword(s):  
Building Blocks ◽  
Ugi Reaction ◽  
One Pot ◽  
Microwave Assisted

scholarly journals Microwave-assisted urea catalyzed Knoevenagel condensation of aldehydes with active methylene compounds

2020 ◽  
Vol 55 (2) ◽  
pp. 159-164
Author(s):  
WT Purba ◽  
PS Roy ◽  
S Jannat ◽  
SA Begum ◽  
MM Rahman
Keyword(s):  
Microwave Irradiation ◽  
Efficient Method ◽  
Knoevenagel Condensation ◽  
Efficient Catalyst ◽  
Microwave Assisted ◽  
Solvent Free Conditions ◽  
Wide Range ◽  
Active Methylene Compounds ◽  
Reaction Proceeds ◽  
Active Methylene

Rapid and efficient method for the synthesis of substituted olefins such as 2-(4-chlorophenylmethylene) malononitrile, 2-(4-hydroxyphenylmethylene) malononitrile and 2-cyano-3-(4-hydroxyphenyl) acrylamide etc under the influence of microwave irradiation are described. Urea has been utilized as an efficient catalyst for the Knoevenagel condensation of aldehydes with acidic active methylene compounds such as malononitrile, ethylcyanoacetate and cyanoacetamide to afford substituted olefins under the influence of microwave irradiation. The reaction proceeds smoothly under mild and solvent free conditions and the products are obtained in good yield. The method is applicable for a wide range of aldehydes including aromatic and heterocyclic substrates. Bangladesh J. Sci. Ind. Res.55(2), 159-164, 2020

scholarly journals Microwave Assisted Reactions of Fluorescent Pyrrolodiazine Building Blocks

Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3760
Author(s):  
Costel Moldoveanu ◽  
Dorina Amariucai-Mantu ◽  
Violeta Mangalagiu ◽  
Vasilichia Antoci ◽  
Dan Maftei ◽  
...  
Keyword(s):  
Spectral Properties ◽  
Building Blocks ◽  
Biological Molecules ◽  
Quantum Yields ◽  
Dipolar Cycloaddition ◽  
Dimethyl Acetylenedicarboxylate ◽  
Microwave Assisted ◽  
Subsequent Step ◽  
Blue Emitters ◽  
Mw Irradiation

We report here the synthesis and optical spectral properties of several new pyrrolodiazine derivatives. The luminescent heterocycles were synthesized by 1,3-dipolar cycloaddition reactions between N-alkylated pyridazine and methylpropiolate or dimethyl acetylenedicarboxylate (DMAD). The pyrrolopyridazine derivatives are blue emitters with moderate quantum yields (around 25%) in the case of pyrrolopyridazines and negligible yet measurable emission for pyrrolophthalazines. In a subsequent step towards including the pyrrolodiazine moiety, given its spectral properties in various macromolecular frameworks such as biological molecules, a subset of the synthetized compounds has been subjected to α-bromination. A selective and efficient way for α-bromination in heterogeneous catalysis of pyrrolodiazine derivatives under microwave (MW) irradiation is presented. We report substantially higher yields under MW irradiation, whereas the solvent amounts required are at least five-fold less compared to classical heating.

Charles Wayne Rees CBE. 15 October 1927 — 21 September 2006

2015 ◽  
Vol 61 ◽  
pp. 351-378
Author(s):  
Christopher J. Moody
Keyword(s):  
Scientific Work ◽  
Building Blocks ◽  
Heterocyclic Chemistry ◽  
Birkbeck College ◽  
Heterocyclic Molecules ◽  
King's College ◽  
Naturally Occurring ◽  
Organic Chemist ◽  
Life Itself ◽  
The University

Charles Rees was an eminent organic chemist. He specialized in the area of heterocyclic chemistry—the study of rings made up of carbon, nitrogen, oxygen and sulphur atoms—an important subject given that many medicines, agrochemicals, dyes and reprographic materials, as well as a very large number of naturally occurring compounds, including the DNA bases, the building blocks of life itself, are heterocyclic molecules. His scientific work was dominated by two overarching themes: reactive intermediates, in particular neutral, electron-deficient species such as carbenes, nitrenes and arynes, and unusual ring systems, particularly strained rings and novel aromatic systems, including those rich in sulphur and nitrogen atoms. Born in 1927, he was educated at Farnham Grammar School, then spent three years at the Royal Aircraft Establishment, before going to University College Southampton (later Southampton University) (BSc 1950, PhD 1953). After a postdoctoral period, he was appointed assistant lecturer at Birkbeck College, London, in 1955, before moving to a lectureship at King’s College, London, and subsequently to chairs at the University of Leicester (1965), the University of Liverpool (1969) and Imperial College, London (1978). He was elected to the Royal Society in 1974 and appointed CBE in 1995. He died in London in 2006.

A New Synthesis of 4,5,6,7-Tetrahydropyrazolo[1,5-c]pyrimidines by a Retro-Mannich Cascade Rearrangement

2014 ◽  
Vol 67 (3) ◽  
pp. 420 ◽  
Author(s):  
Raffaele Colombo ◽  
Kyu Ok Jeon ◽  
Donna M. Huryn ◽  
Matthew G. LaPorte ◽  
Peter Wipf
Keyword(s):  
Mannich Reaction ◽  
Medicinal Chemistry ◽  
Hydrolysis Product ◽  
Building Blocks ◽  
Biological Applications ◽  
Heterocyclic Chemistry ◽  
New Synthesis ◽  
Rearrangement Process

We discovered a new retro-Mannich reaction of in situ prepared pyrazolopyridines to give pyrazolopyrimidines that have hitherto been underrepresented in the heterocyclic chemistry literature. The isolation of a linear hydrolysis product supports a mechanistic hypothesis for this rearrangement process. In order to establish a broader access and explore potential biological applications for these medicinal chemistry building blocks, we investigated the scope of the reaction and generated small amine- as well as amide-based libraries through reductive aminations and amide couplings, respectively.

Microwave-Assisted Heterocyclic Chemistry for Undergraduate Organic Laboratory

2006 ◽  
Vol 83 (4) ◽  
pp. 632 ◽  
Author(s):  
Robert Musiol ◽  
Bozena Tyman-Szram ◽  
Jaroslaw Polanski
Keyword(s):  
Heterocyclic Chemistry ◽  
Microwave Assisted ◽  
Organic Laboratory

ChemInform Abstract: Efficient Ytterbium Triflate Catalyzed Microwave-Assisted Synthesis of 3-Acylacrylic Acid Building Blocks.

ChemInform ◽  
2009 ◽  
Vol 40 (13) ◽  
Author(s):  
Nikita V. Tolstoluzhsky ◽  
Nikolay Yu. Gorobets ◽  
Nadezhda N. Kolos ◽  
Sergey M. Desenko
Keyword(s):  
Building Blocks ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Ytterbium Triflate

Microwave Assisted Synthesis of N-(ethoxycarbonylmethyl)-nucleobases: Building Blocks for PNAs

2005 ◽  
Vol 2005 (3) ◽  
pp. 167-168 ◽  
Author(s):  
Gui-Rong Qu ◽  
Yong Li ◽  
Su-Hui Han
Keyword(s):  
Microwave Irradiation ◽  
Nucleic Acids ◽  
Peptide Nucleic Acids ◽  
Building Blocks ◽  
Microwave Assisted Synthesis ◽  
Ethyl Bromoacetate ◽  
Microwave Assisted

The synthesis of N1/N9- (Ethoxycarbonylmethyl)pyrimidine/purine using as synthons for peptide nucleic acids has been described. Microwave irradiation provided the desired products by alkylation of the appropriately protected natural and substituted nucleobases with ethyl bromoacetate within 4–7 min in 48–85% yields.

scholarly journals Practical and Regioselective Synthesis of C4-Alkylated Pyridines

2021 ◽  
Author(s):  
jin choi ◽  
Gabriele Laudadio ◽  
Edouard Godineau ◽  
Phil Baran
Keyword(s):  
Carboxylic Acid ◽  
Late Stage ◽  
Building Blocks ◽  
Regioselective Synthesis ◽  
Heterocyclic Chemistry ◽  
Blocking Group ◽  
Functionalized Materials

The direct position-selective C–4 alkylation of pyridines has been a longstanding challenge in heterocyclic chemistry, particularly from pyridine itself. Historically this has been addressed using pre-functionalized materials to avoid overalkylation and mixtures of regioisomers. This study reports the invention of a simple maleate-derived blocking group for pyridines that enables exquisite control for Minisci-type decarboxylative alkylation at C–4 that allows for inexpensive access to these valuable building blocks. The method is employed on a variety of different pyridines and carboxylic acid alkyl donors, is operationally simple, scalable, and is applied to access known structures in a rapid and inexpensive fashion. Finally, this work points to an interesting strategic departure for the use of Minisci chemistry at the earliest possible stage (native pyridine) rather than current dogma that almost exclusively employs Minisci as a late-stage functionalization technique.

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