Synthesis Of Bioactive Heterocycles Research Articles

Ultrasound-assisted transition-metal-free catalysis: a sustainable route towards the synthesis of bioactive heterocycles.

Heterocycles of synthetic and natural origin are a well-established class of compounds representing a broad range of organic molecules that constitute over 60% of drugs and agrochemicals in the market or research pipeline. Considering the vast abundance of these structural motifs, the development of chemical processes providing easy access to novel complex target molecules by introducing environmentally benign conditions with the main focus on improving the cost-effectiveness of the chemical transformation is highly demanding and challenging. Accordingly, sonochemistry appears to be an excellent alternative and a highly feasible environmentally benign energy input that has recently received considerable and steadily increasing interest in organic synthesis. However, the involvement of transition-metal-catalyst(s) in a chemical process often triggers an unintended impact on the greenness or sustainability of the transformation. Consequently, enormous efforts have been devoted to developing metal-free routes for assembling various heterocycles of medicinal interest, particularly under ultrasound irradiation. The present review article aims to demonstrate a brief overview of the current progress accomplished in the ultrasound-assisted synthesis of pharmaceutically relevant diverse heterocycles using transition-metal-free catalysis.

Synthesis of Bioactive Heterocycles from 6-amino-4-(2-chloro-5-nitrophenyl)-3-methyl-1,4-dihydropyrano[2,3-c] pyrazole-5-carbonitrile

Enaminonitrile derivative, 6-amino-4-(2-chloro-5-nitrophenyl)-3-methyl-1,4-dihydropyrano[2,3- c ]pyrazole-5-carbonitrile ( 1) was synthesized. This compound was utilized as a building block for the synthesis of new 3-methylpyrazolopyran moiety incorporated with different heterocycles involving pyrimidinone, oxazinone, and iminopyrimidine, in addition to novel derivatives including diacetyl derivative ( 5) , benzoyl derivative ( 6) , carbamodithioic acid ( 10) and urea derivative ( 13) . Spectral techniques, FT-IR, 1 H-NMR and mass spectroscopy and elemental analysis were used to characterize the synthesized compounds. Screening and evaluation of these products as antimicrobial agents showed that the derivatives 5 , 6 , 10 , and 13 possess a potent activity.

Synthesis of Bioactive Heterocycles from 6-Amino-4-(2-chloro-5-nitrophenyl)- 3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile

Synthesis of Bioactive Heterocycles from 6-Amino-4-(2-chloro-5-nitrophenyl)- 3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile

Current Trends towards the Synthesis of Bioactive Heterocycles and Natural Products Using 1,3-Dipolar Cycloadditions (1,3-DC) with Azomethine Ylides

This review summarizes the trends in the formation of complex or not so complex heterocyclic structures through 1,3-dipolar cy­cloadditions of azomethine ylides. Diastereo- and enantioselective processes as well as non-asymmetric cycloadditions constitute very important synthetic tools for achieving these compounds. This review covers the literature from 2015 through 2016 and organizes the research in terms of biologically important heterocycles and natural products from cascade 1,3-dipolar cycloadditions of azomethine ylides to the simpler forms of 1,3-dipolar cycloaddition.1 Introduction2 Synthesis of Spirooxindoles3 Synthesis of Spiropyrrolidines4 Synthesis of Spiropiperidines and Piperidines5 Synthesis of Pyrrolidines and Fused Pyrrolidines6 Synthesis of Pyrrolizidines and Indolizidines7 Synthesis of Quinolone and Isoquinolines8 Conclusions

ChemInform Abstract: Recent Advancement of Ullmann‐Type Coupling Reactions in the Formation of C—C Bond

AbstractReview: 64 refs.

Recent advancement of Ullmann-type coupling reactions in the formation of C–C bond

The present text discussed about the recent developments and applications of the Ullmann reaction in respect of the C–C bond formation. The major drawback of the Ullmann reaction, i.e., harsh reaction condition has recently been overcome with the development of various synthetic methodologies. Green synthetic methodologies such as metal-, ligand-, and additive free conditions, recyclable heterogenous catalysts, microwave- and ultrasound-assisted synthesis, etc. have got special importance in this field. This text lucidly describes all these recently developed synthetic methodologies which make the century old Ullmann reaction much efficient, effective, economical and attractive in the field of synthetic organic chemistry. On-surface Ullmann coupling for the C–C bond formation, i.e., invoking C–C coupling reactions on a reactive surface has been discussed. All such developments of the Ullmann C–C coupling facilitate its application in the synthesis of bio-active heterocycles, drug-like molecules and natural products which has also been discussed in this text.

ChemInform Abstract: Microwave‐Assisted Synthesis of Bioactive Heterocycles in Aqueous Media

AbstractReview: 75 refs.

Synthesis of bioactive heterocycles: tandem reaction of 4- N-(4′-aryloxybut-2′-ynyl), N-methylaminocoumarin with 3-chloroperoxybenzoic acid

A number of 4- N-(4′-aryloxybut-2′-ynyl), N-methylaminocoumarins ( 4a– e ) on treatment with one equivalent of 3-chloroperoxybenzoic acid at 0–5°C for 10 min and then stirring at rt for 10 h afforded pyrrolo[3,2- c]coumarin derivatives in 70–75% yields. The 4- N-(4′-aryloxybut-2′-ynyl), N-methylaminocoumarins 4a– e were in turn prepared from 4-tosyloxycoumarin ( 2 ) and (4-aryloxybut-2-ynyl)- N-methylamine ( 3a– e ).

ChemInform Abstract: Synthesis of Bioactive Heterocycles: One‐Pot Regioselective Synthesis of Pyrano[3,2‐f]benzo[b]thiophene Derivatives.

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Synthesis of bioactive heterocycles: One pot regioselective synthesis of pyrano[3,2- f]benzo[ b]thiophene derivatives

Regioselective synthesis of hitherto unreported pyrano[3,2- f]benzo[ b]thiophene derivatives ( 8a-f) in 90–95% yields are reported by the application of a less studied rearrangement of 6-(4-aryloxybut-2-ynylthio)[1]benzopyran-2-ones ( 5a-f) via oxidation with m-chloroperoxybenzoic acid followed by thermal rearrangement and treatment with methanol. Substrates 5a-f are prepared by the reaction of 6-mercaptocoumarin (unstable) with 1-aryloxy-4-chlorobut-2-ynes ( 4) in refluxing acetone in the presence of anhydrous potassium carbonate and sodium iodide. 6-Mercaptocoumarin ( 3) is in turn prepared by the zinc-acid reduction of the disulfide ( 2) obtained by the reaction of the diazotised 6-aminocoumarin ( 1) with potassium ethylxanthate followed by decomposition. Pyrano[3,2- f]-benzo[ b]thiophene derivatives ( 8a-f) are easily converted to 1-acetylpyrano[3,2- f]benzo[ b]thiophene-7-one ( 12) when refluxed in acetic acid in the presence of catalytic amount of conc. sulfuric acid for 4 h.