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11 pages, 1505 KiB

Open AccessArticle

2-Amino-1,3-benzothiazole: Endo N-Alkylation with α-Iodo Methyl Ketones Followed by Cyclization

by Ivan A. Dorofeev, Larisa V. Zhilitskaya, Nina O. Yarosh and Bagrat A. Shainyan

Molecules 2023, 28(5), 2093; https://doi.org/10.3390/molecules28052093 - 23 Feb 2023

Cited by 1 | Viewed by 1303

Abstract

Reactions of 2-amino-1,3-benzothiazole with aliphatic, aromatic and heteroaromatic α-iodoketones in the absence of bases or catalysts have been studied. The reaction proceeds by N-alkylation of the endocyclic nitrogen atom followed by intramolecular dehydrative cyclization. The regioselectivity is explained and the mechanism of the [...] Read more.

Reactions of 2-amino-1,3-benzothiazole with aliphatic, aromatic and heteroaromatic α-iodoketones in the absence of bases or catalysts have been studied. The reaction proceeds by N-alkylation of the endocyclic nitrogen atom followed by intramolecular dehydrative cyclization. The regioselectivity is explained and the mechanism of the reaction is proposed. A number of new linear and cyclic iodide and triiodide benzothiazolium salts have been obtained and their structure proved by NMR and UV spectroscopy. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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9 pages, 4537 KiB

Open AccessCommunication

A Concise Synthesis of Pyrrole-Based Drug Candidates from α-Hydroxyketones, 3-Oxobutanenitrile, and Anilines

by Mengxin Xia, Mardi Santoso, Ziad Moussa and Zaher M. A. Judeh

Molecules 2023, 28(3), 1265; https://doi.org/10.3390/molecules28031265 - 28 Jan 2023

Cited by 2 | Viewed by 1627

Abstract

A simple and concise three-component synthesis of a key pyrrole framework was developed from the reaction between α-hydroxyketones, oxoacetonitriles, and anilines. The synthesis was used to obtain several pyrrole-based drug candidates, including COX-2 selective NSAID, antituberculosis lead candidates BM212, BM521, and BM533, as [...] Read more.

A simple and concise three-component synthesis of a key pyrrole framework was developed from the reaction between α-hydroxyketones, oxoacetonitriles, and anilines. The synthesis was used to obtain several pyrrole-based drug candidates, including COX-2 selective NSAID, antituberculosis lead candidates BM212, BM521, and BM533, as well as several analogues. This route has potential to obtain diverse libraries of these pyrrole candidates in a concise manner to develop optimum lead compounds. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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10 pages, 1661 KiB

Open AccessArticle

Nickel-Catalyzed Suzuki Coupling of Phenols Enabled by SuFEx of Tosyl Fluoride

by Huimin Wang, Shuqin Zhang, Minling Xü and Gang Zou

Molecules 2023, 28(2), 636; https://doi.org/10.3390/molecules28020636 - 07 Jan 2023

Viewed by 2296

Abstract

A practical and efficient Suzuki coupling of phenols has been developed by using trans-NiCl(o-Tol)(PCy₃)₂/2PCy₃ as a catalyst in the presence of tosyl fluoride as an activator. The key for the direct use of phenols lies [...] Read more.

A practical and efficient Suzuki coupling of phenols has been developed by using trans-NiCl(o-Tol)(PCy₃)₂/2PCy₃ as a catalyst in the presence of tosyl fluoride as an activator. The key for the direct use of phenols lies in the compatibility of the nickel catalyst with tosyl fluoride (TsF) and its sulfur(VI) fluoride exchange (SuFEx) with C_Ar-OH. Water has been found to improve the one-pot process remarkably. The steric and electronic effects and the functional group compatibility of the one-pot Suzuki coupling of phenols appear to be comparable to the conventional one of pre-prepared aryl tosylates. A series of electronically and sterically various biaryls could be obtained in good to excellent yields by using 3–10 mol% loading of the nickel catalyst. The applications of this one-pot procedure in chemoselective derivatization of complex molecules have been demonstrated in 3-phenylation of estradiol and estrone. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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10 pages, 2051 KiB

Open AccessArticle

Dimerization/Elimination of β-Styrylmalonates under Action of TiCl₄

by D. D. Borisov, G. R. Chermashentsev, K. V. Potapov, R. A. Novikov and Yu. V. Tomilov

Molecules 2023, 28(1), 270; https://doi.org/10.3390/molecules28010270 - 29 Dec 2022

Viewed by 1060

Abstract

A new type of dimerization of dimethyl (β-styryl)malonates in the presence of TiCl₄ accompanied by elimination of a methanol molecule was discovered. Selective methods for the synthesis of substituted trimethyl 4-hydroxy-[1,1′-biaryl]-3,3,5(2H)-tricarboxylates and trimethyl 7-hydroxy-9,10-dihydro-5,9-methanobenzo[8]annulene-6,8,8(5H)-tricarboxylates were developed. The regularities [...] Read more.

A new type of dimerization of dimethyl (β-styryl)malonates in the presence of TiCl₄ accompanied by elimination of a methanol molecule was discovered. Selective methods for the synthesis of substituted trimethyl 4-hydroxy-[1,1′-biaryl]-3,3,5(2H)-tricarboxylates and trimethyl 7-hydroxy-9,10-dihydro-5,9-methanobenzo[8]annulene-6,8,8(5H)-tricarboxylates were developed. The regularities of the occurring processes were determined and a similar reaction of β-styrylmalonate with benzylidenemalonate in the presence of TiCl₄ was performed in the scope of the suggested mechanism. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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41 pages, 6808 KiB

Open AccessArticle

Powerful Potential of Polyfluoroalkyl-Containing 4-Arylhydrazinylidenepyrazol-3-ones for Pharmaceuticals

by Yanina V. Burgart, Natalia A. Elkina, Evgeny V. Shchegolkov, Olga P. Krasnykh, Galina F. Makhaeva, Galina A. Triandafilova, Sergey Yu. Solodnikov, Natalia P. Boltneva, Elena V. Rudakova, Nadezhda V. Kovaleva, Olga G. Serebryakova, Mariya V. Ulitko, Sophia S. Borisevich, Natalia A. Gerasimova, Natalia P. Evstigneeva, Sergey A. Kozlov, Yuliya V. Korolkova, Artem S. Minin, Anna V. Belousova, Evgenii S. Mozhaitsev, Artem M. Klabukov and Victor I. Saloutin Show full author list Hide full author list

Molecules 2023, 28(1), 59; https://doi.org/10.3390/molecules28010059 - 21 Dec 2022

Cited by 4 | Viewed by 2432

Abstract

4-Arylhydrazinylidene-5-(polyfluoroalkyl)pyrazol-3-ones (4-AHPs) were found to be obtained by the regiospecific cyclization of 2-arylhydrazinylidene-3-(polyfluoroalkyl)-3-oxoesters with hydrazines, by the azo coupling of 4-nonsubstituted pyrazol-5-oles with aryldiazonium chlorides or by the firstly discovered acid-promoted self-condensation of 2-arylhydrazinylidene-3-oxoesters. All the 4-AHPs had an acceptable ADME profile. Varying [...] Read more.

4-Arylhydrazinylidene-5-(polyfluoroalkyl)pyrazol-3-ones (4-AHPs) were found to be obtained by the regiospecific cyclization of 2-arylhydrazinylidene-3-(polyfluoroalkyl)-3-oxoesters with hydrazines, by the azo coupling of 4-nonsubstituted pyrazol-5-oles with aryldiazonium chlorides or by the firstly discovered acid-promoted self-condensation of 2-arylhydrazinylidene-3-oxoesters. All the 4-AHPs had an acceptable ADME profile. Varying the substituents in 4-AHPs promoted the switching or combining of their biological activity. The polyfluoroalkyl residue in 4-AHPs led to the appearance of an anticarboxylesterase action in the micromolar range. An NH-fragment and/or methyl group instead of the polyfluoroalkyl one in the 4-AHPs promoted antioxidant properties in the ABTS, FRAP and ORAC tests, as well as anti-cancer activity against HeLa that was at the Doxorubicin level coupled with lower cytotoxicity against normal human fibroblasts. Some Ph-N-substituted 4-AHPs could inhibit the growth of N. gonorrhoeae bacteria at MIC 0.9 μg/mL. The possibility of using 4-AHPs for cell visualization was shown. Most of the 4-AHPs exhibited a pronounced analgesic effect in a hot plate test in vivo at and above the diclofenac and metamizole levels except for the ones with two chlorine atoms in the aryl group. The methylsulfonyl residue was proved to raise the anti-inflammatory effect also. A mechanism of the antinociceptive action of the 4-AHPs through blocking the TRPV1 receptor was proposed and confirmed using in vitro experiment and molecular docking. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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14 pages, 4267 KiB

Open AccessArticle

Synthesis and Characterization of Novel 2-(1,2,3-Triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazoles and 2-(4,5-Dihydro-1H-pyrazol-1-yl)-4-(1H-1,2,3-triazol-4-yl)thiazoles

by Benson M. Kariuki, Bakr F. Abdel-Wahab, Hanan A. Mohamed, Mohamed S. Bekheit and Gamal A. El-Hiti

Molecules 2022, 27(24), 8904; https://doi.org/10.3390/molecules27248904 - 14 Dec 2022

Cited by 10 | Viewed by 1523

Abstract

Reactions of 1-(5-methyl)-1H-1,2,3-triazol-4-yl)ethan-1-ones and benzaldehydes in ethanol under basic conditions gave the corresponding chalcones. Reactions of the chalcones combined with thiosemicarbazide in dry ethanol containing sodium hydroxide afforded the corresponding pyrazolin-N-thioamides. Reactions of the synthesized pyrazolin-N-thioamides and [...] Read more.

Reactions of 1-(5-methyl)-1H-1,2,3-triazol-4-yl)ethan-1-ones and benzaldehydes in ethanol under basic conditions gave the corresponding chalcones. Reactions of the chalcones combined with thiosemicarbazide in dry ethanol containing sodium hydroxide afforded the corresponding pyrazolin-N-thioamides. Reactions of the synthesized pyrazolin-N-thioamides and several ketones (namely, ethyl 2-chloro-3-oxobutanoate, 2-bromoacetylbenzofuran, and hydrazonoyl chloride) gave the corresponding novel 2-(1,2,3-triazol-4-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazoles in high yields (77–90%). Additionally, 2-(4,5-dihydro-1H-pyrazol-1-yl)-4-(1H-1,2,3-triazol-4-yl)thiazoles were obtained in high yields (84–87%) from reactions with N-pyrazoline-thioamides and 4-bromoacetyl-1,2,3-triazoles under basic conditions. The structures of six of the newly synthesized heterocycles were confirmed by X-ray crystallography. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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14 pages, 3958 KiB

Open AccessArticle

Substituent-Dependent Divergent Synthesis of 2-(3-Amino-2,4-dicyanophenyl)pyrroles, Pyrrolyldienols and 3-Amino-1-acylethylidene-2-cyanopyrrolizines via Reaction of Acylethynylpyrroles with Malononitrile

by Maxim D. Gotsko, Ivan V. Saliy, Igor A. Ushakov, Lyubov N. Sobenina and Boris A. Trofimov

Molecules 2022, 27(23), 8528; https://doi.org/10.3390/molecules27238528 - 03 Dec 2022

Viewed by 1135

Abstract

An efficient method for the synthesis of pharmaceutically and high-tech prospective 2-(3-amino-2,4-dicyanophenyl)pyrroles (in up to 88% yield) via the reaction of easily available substituted acylethynylpyrroles with malononitrile has been developed. The reaction proceeds in the KOH/MeCN system at 0 °C for 2 h. [...] Read more.

An efficient method for the synthesis of pharmaceutically and high-tech prospective 2-(3-amino-2,4-dicyanophenyl)pyrroles (in up to 88% yield) via the reaction of easily available substituted acylethynylpyrroles with malononitrile has been developed. The reaction proceeds in the KOH/MeCN system at 0 °C for 2 h. In the case of 2-acylethynylpyrroles without substituents in the pyrrole ring, the reaction changes direction: instead of the target 2-(3-amino-2,4-dicyanophenyl)pyrroles, the unexpected formation of pyrrolyldienols and products of their intramolecular cyclization, 3-amino-1-acylethylidene-2-cyanopyrrolizines, is observed. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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15 pages, 5926 KiB

Open AccessArticle

Exploring the Optoelectronic Properties of D-A and A-D-A 2,2′-bi[3,2-b]thienothiophene Derivatives

by Levi Gabrian, Gavril-Ionel Giurgi, Ioan Stroia, Elena Bogdan, Andreea Petronela Crişan, Niculina Daniela Hădade, Ion Grosu and Anamaria Terec

Molecules 2022, 27(23), 8463; https://doi.org/10.3390/molecules27238463 - 02 Dec 2022

Cited by 1 | Viewed by 1440

Abstract

The synthesis of some novel donor-acceptor and acceptor-donor-acceptor systems containing a 2,2′-bi[3,2-b]thienothiophene donor block and various electron-accepting units is described alongside their photophysical properties studied using electrochemistry, optical spectroscopy and theoretical calculations. The obtained results show that the energy levels can [...] Read more.

The synthesis of some novel donor-acceptor and acceptor-donor-acceptor systems containing a 2,2′-bi[3,2-b]thienothiophene donor block and various electron-accepting units is described alongside their photophysical properties studied using electrochemistry, optical spectroscopy and theoretical calculations. The obtained results show that the energy levels can be modulated by changing the strength of the acceptor unit. Among the three investigated end-groups, 1,1-dicyanomethylene-3-indanone exhibited the largest bathochromic shift and the lowest band gap suggesting the strongest electron-withdrawing character. Moreover, the emissive properties of the investigated systems vary greatly with the nature of the terminal group and are generally lower compared to their precursor aldehyde derivatives. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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10 pages, 2686 KiB

Open AccessArticle

Synthesis and the Crystal Structure of a New Chiral 1D Metal–Organic Coordination Polymer Based on L-Prolineamide-Substituted Diarylacetylenedicarboxylic Acid Derivative

by Vladimir V. Veselovsky, Vera I. Isaeva, Vera D. Nissenbaum, Leonid M. Kustov and Vladimir V. Chernyshev

Molecules 2022, 27(23), 8376; https://doi.org/10.3390/molecules27238376 - 30 Nov 2022

Viewed by 1243

Abstract

The new homochiral 1D metal–organic coordination polymer [Cu₂(EDPB)•H₂O]_n was synthesized starting from the original 3,3′-ethyne-1,2-diylbis[6-(L-prolylamino)benzoic acid] (H₄EDPB). The unique crystal structure of the new compound was established by powder X-ray diffraction. The [Cu₂ [...] Read more.

The new homochiral 1D metal–organic coordination polymer [Cu₂(EDPB)•H₂O]_n was synthesized starting from the original 3,3′-ethyne-1,2-diylbis[6-(L-prolylamino)benzoic acid] (H₄EDPB). The unique crystal structure of the new compound was established by powder X-ray diffraction. The [Cu₂(EDPB)•H₂O]_n system shows catalytic activity and enantioselectivity in a Henry reaction of p-nitrobenzaldehyde with nitromethane. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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27 pages, 3588 KiB

Open AccessFeature PaperArticle

SnAr Reactions of 2,4-Diazidopyrido[3,2-d]pyrimidine and Azide-Tetrazole Equilibrium Studies of the Obtained 5-Substituted Tetrazolo[1,5-a]pyrido[2,3-e]pyrimidines

by Kristaps Leškovskis, Anatoly Mishnev, Irina Novosjolova and Māris Turks

Molecules 2022, 27(22), 7675; https://doi.org/10.3390/molecules27227675 - 08 Nov 2022

Cited by 1 | Viewed by 2063

Abstract

A straightforward method for the synthesis of 5-substituted tetrazolo[1,5-a]pyrido[2,3-e]pyrimidines from 2,4-diazidopyrido[3,2-d]pyrimidine in SnAr reactions with N-, O-, and S- nucleophiles has been developed. The various N- and S-substituted products were [...] Read more.

A straightforward method for the synthesis of 5-substituted tetrazolo[1,5-a]pyrido[2,3-e]pyrimidines from 2,4-diazidopyrido[3,2-d]pyrimidine in SnAr reactions with N-, O-, and S- nucleophiles has been developed. The various N- and S-substituted products were obtained with yields from 47% to 98%, but the substitution with O-nucleophiles gave lower yields (20–32%). Furthermore, the fused tetrazolo[1,5-a]pyrimidine derivatives can be regarded as 2-azidopyrimidines and functionalized in copper(I)-catalyzed azide-alkyne dipolar cycloaddition (CuAAC) and Staudinger reactions due to the presence of a sufficient concentration of the reactive azide tautomer in solution. In total, seven products were fully characterized by their single crystal X-ray studies, while five of them were representatives of the tetrazolo[1,5-a]pyrido[2,3-e]pyrimidine heterocyclic system. Equilibrium constants and thermodynamic values were determined using variable temperature ¹H NMR and are in agreement of favoring the tetrazole tautomeric form (ΔG₂₉₈ = −3.33 to −7.52 (kJ/mol), ΔH = −19.92 to −48.02 (kJ/mol) and ΔS = −43.74 to −143.27 (J/mol·K)). The key starting material 2,4-diazidopyrido[3,2-d]pyrimidine presents a high degree of tautomerization in different solvents. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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14 pages, 4030 KiB

Open AccessArticle

Molecular Hybrids of Pyazolo[3,4-b]pyridine and Triazole: Design, Synthesis and In Vitro Antibacterial Studies

by Narasimha Rao Bandaru, Parameshwar Makam, Parameswari Akshinthala, Naresh Kumar Katari, Venkanna Banoth, Balakrishna Kolli and Rambabu Gundla

Molecules 2022, 27(21), 7647; https://doi.org/10.3390/molecules27217647 - 07 Nov 2022

Cited by 3 | Viewed by 1509

Abstract

Antimicrobial resistance is on the rise, and there aren’t enough new treatments to combat it. This might send the modern world back to the pre-antibiotic age. The molecular hybrids of pyrazolo[3,4-b]pyridine and triazole have been designed, synthesized, and analyzed for their [...] Read more.

Antimicrobial resistance is on the rise, and there aren’t enough new treatments to combat it. This might send the modern world back to the pre-antibiotic age. The molecular hybrids of pyrazolo[3,4-b]pyridine and triazole have been designed, synthesized, and analyzed for their drug-like molecule nature and in vitro analyses for their inhibition potentials against S. aureus and K. pneumoniae. The compounds 24 and 27 have been identified as the high potential molecules in this series based on in vitro experiments. Compound 24 has zone of inhibition values of 15 ± 0.82 mm and 14 ± 0.7 mm, whilst compound 27 has zone of inhibition values of 18 ± 0.95 mm and 16 ± 0.82 mm against S. aureus and K. pneumoniae, respectively. MIC and MIB values for compounds 24 and 27 against S. aureus and K. pneumoniae are 0.25 and 0.5, respectively. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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12 pages, 2874 KiB

Open AccessArticle

Copper-Catalyzed Diboron-Mediated cis-Semi-Hydrogenation of Alkynes under Facile Conditions

by Yuxi Zeng, Honggang Zhang, Daofan Ma and Guangwei Wang

Molecules 2022, 27(21), 7213; https://doi.org/10.3390/molecules27217213 - 25 Oct 2022

Viewed by 1397

Abstract

Cis-alkenes are ubiquitous in biological molecules, which makes it greatly significant to develop efficient methods toward construction of cis-olefins. Herein, we reported a facile semi-hydrogenation of alkynes to cis-alkenes in an efficient way with cuprous bromide/tributylphosphine as the catalyst and [...] Read more.

Cis-alkenes are ubiquitous in biological molecules, which makes it greatly significant to develop efficient methods toward construction of cis-olefins. Herein, we reported a facile semi-hydrogenation of alkynes to cis-alkenes in an efficient way with cuprous bromide/tributylphosphine as the catalyst and bis(pinacolato)diboron/methanol as the hydrogen donor. The method features convenient and facile reaction conditions, wide substrate scope, high yields, and high stereoselectivity. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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14 pages, 2647 KiB

Open AccessArticle

Metal-Free Synthesis of Carbamoylated Chroman-4-Ones via Cascade Radical Annulation of 2-(Allyloxy)arylaldehydes with Oxamic Acids

by Long-Yong Xie, Sha Peng, Li-Hua Yang and Xiao-Wen Liu

Molecules 2022, 27(20), 7049; https://doi.org/10.3390/molecules27207049 - 19 Oct 2022

Cited by 5 | Viewed by 1235

Abstract

An efficient and straightforward approach for the synthesis of carbamoylated chroman-4-ones has been well-developed. The reaction is triggered through the generation of carbamoyl radicals from oxamic acids under metal-free conditions, which subsequently undergoes decarboxylative radical cascade cyclization on 2-(allyloxy)arylaldehydes to afford various amide-containing [...] Read more.

An efficient and straightforward approach for the synthesis of carbamoylated chroman-4-ones has been well-developed. The reaction is triggered through the generation of carbamoyl radicals from oxamic acids under metal-free conditions, which subsequently undergoes decarboxylative radical cascade cyclization on 2-(allyloxy)arylaldehydes to afford various amide-containing chroman-4-one scaffolds with high functional group tolerance and a broad substrate scope. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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12 pages, 2043 KiB

Open AccessArticle

Heterocyclization of Bis(2-chloroprop-2-en-1-yl)sulfide in Hydrazine Hydrate–KOH: Synthesis of Thiophene and Pyrrole Derivatives

by Igor B. Rozentsveig, Valentina S. Nikonova, Victor V. Manuilov, Igor A. Ushakov, Tatyana N. Borodina, Vladimir I. Smirnov and Nikolay A. Korchevin

Molecules 2022, 27(20), 6785; https://doi.org/10.3390/molecules27206785 - 11 Oct 2022

Cited by 2 | Viewed by 1132

Abstract

The article is devoted to heterocyclization of bis(2-chloroprop-2-en-1-yl)sulfide which proceeds in hydrazine hydrate–alkali medium and leads to formation of thiophene and pyrrole derivatives: previously described 4,5,9,10-tetrahydrocycloocta[1,2-c;5,8-c’]dithiophene, as well as unknown hydrazone of 5-methylidene-3-methyldihydrothiophen-2-one and 1-amino-2-(propynylsulfanylpropenylsulfanyl)-3,5-dimethylpyrrole. Tentative mechanisms for the formation of the heterocyclic [...] Read more.

The article is devoted to heterocyclization of bis(2-chloroprop-2-en-1-yl)sulfide which proceeds in hydrazine hydrate–alkali medium and leads to formation of thiophene and pyrrole derivatives: previously described 4,5,9,10-tetrahydrocycloocta[1,2-c;5,8-c’]dithiophene, as well as unknown hydrazone of 5-methylidene-3-methyldihydrothiophen-2-one and 1-amino-2-(propynylsulfanylpropenylsulfanyl)-3,5-dimethylpyrrole. Tentative mechanisms for the formation of the heterocyclic products are discussed. Obtained hydrazone of 5-methylidene-3-methyldihydrothiophen-2-one was used for the synthesis of a range of azine derivatives and in oxidation process with SeO₂. The found reactions open up expedient approaches to the formation of various hardly accessible thiophene and pyrrole compounds from 2,3-dichloropropene and elemental sulfur as starting reagents. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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12 pages, 1120 KiB

Open AccessArticle

Iodine-Mediated Alkoxyselenylation of Alkenes and Dienes with Elemental Selenium

by Evgeny O. Kurkutov and Bagrat A. Shainyan

Molecules 2022, 27(19), 6169; https://doi.org/10.3390/molecules27196169 - 20 Sep 2022

Cited by 2 | Viewed by 1242

Abstract

A one-pot synthesis of linear and cyclic β-alkoxyselenides is developed through the iodine-mediated three-component reaction of elemental selenium with alkenes (dienes) and alcohols. Selenylation of 1,5-hexadiene gives 2,5-di(methoxymethyl)tetrahydroselenophene and 2-methoxy-6-(methoxymethyl)tetrahydro-2H-selenopyran via the 5-exo-trig and 6-endo-trig cyclization. 1,7-Octadiene affords only [...] Read more.

A one-pot synthesis of linear and cyclic β-alkoxyselenides is developed through the iodine-mediated three-component reaction of elemental selenium with alkenes (dienes) and alcohols. Selenylation of 1,5-hexadiene gives 2,5-di(methoxymethyl)tetrahydroselenophene and 2-methoxy-6-(methoxymethyl)tetrahydro-2H-selenopyran via the 5-exo-trig and 6-endo-trig cyclization. 1,7-Octadiene affords only linear 1:2 adduct with two terminal double bonds. 1,5-Cyclooctadiene results in one diastereomer of 2,6-dialkoxy-9-selenabicyclo [3.3.1]nonanes via 6-exo-trig cyclization. With 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane, the first ring-substituted representative of a very rare class of heterocycles, 1,4,2,6-oxaselenadisilinanes, was obtained at a high yield. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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13 pages, 2943 KiB

Open AccessArticle

Scalable (Enantioselective) Syntheses of Novel 3-Methylated Analogs of Pazinaclone, (S)-PD172938 and Related Biologically Relevant Isoindolinones

by Antonia Di Mola, Giorgia Nicastro, Lorenzo Serusi, Rosanna Filosa, Mario Waser and Antonio Massa

Molecules 2022, 27(17), 5647; https://doi.org/10.3390/molecules27175647 - 01 Sep 2022

Cited by 4 | Viewed by 1347

Abstract

Herein, we report the application of an efficient and practical K₂CO₃ promoted cascade reaction of 2-acetylbenzonitrile in the synthesis of novel 3-methylated analogs of Pazinaclone and PD172938, belonging to isoindolinones heterocyclic class bearing a tetrasubstituted stereocenter. Organocatalytic asymmetric synthesis of [...] Read more.

Herein, we report the application of an efficient and practical K₂CO₃ promoted cascade reaction of 2-acetylbenzonitrile in the synthesis of novel 3-methylated analogs of Pazinaclone and PD172938, belonging to isoindolinones heterocyclic class bearing a tetrasubstituted stereocenter. Organocatalytic asymmetric synthesis of the key intermediate and its transformation into highly enantioenriched 3-methylated analog of (S)-PD172938 was also developed. These achievements can be of particular interest also for medicinal chemistry, since the methyl group is a very useful structural modification in the rational design of new and more effective bioactive compounds. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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15 pages, 3027 KiB

Open AccessArticle

Sunlight Induced and Recyclable g-C₃N₄ Catalyzed C-H Sulfenylation of Quinoxalin-2(1H)-Ones

by Sha Peng, Jiao Liu, Li-Hua Yang and Long-Yong Xie

Molecules 2022, 27(15), 5044; https://doi.org/10.3390/molecules27155044 - 08 Aug 2022

Cited by 6 | Viewed by 1599

Abstract

A sunlight-promoted sulfenylation of quinoxalin-2(1H)-ones using recyclable graphitic carbon nitride (g-C₃N₄) as a heterogeneous photocatalyst was developed. Using the method, various 3-sulfenylated quinoxalin-2(1H)-ones were obtained in good to excellent yields under an ambient air atmosphere. [...] Read more.

A sunlight-promoted sulfenylation of quinoxalin-2(1H)-ones using recyclable graphitic carbon nitride (g-C₃N₄) as a heterogeneous photocatalyst was developed. Using the method, various 3-sulfenylated quinoxalin-2(1H)-ones were obtained in good to excellent yields under an ambient air atmosphere. Moreover, the heterogeneous catalyst can be recycled at least six times without significant loss of activity. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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Review

Jump to: Research

16 pages, 2152 KiB

Open AccessReview

Recent Advances in Asymmetric Catalysis Associated with B(C₆F₅)₃

by Ziye Zhan, Jiale Yan, Zhiyou Yu and Lei Shi

Molecules 2023, 28(2), 642; https://doi.org/10.3390/molecules28020642 - 08 Jan 2023

Cited by 3 | Viewed by 1734

Abstract

The prevalence and significance of asymmetric catalysis in the modern medicinal industry has been witnessed in recent years, which have already been used to manufacture the (S)-Naproxen and the (S)-Propranolol. With matched specificities such as the Lewis acidity and steric bulk, B(C₆ [...] Read more.

The prevalence and significance of asymmetric catalysis in the modern medicinal industry has been witnessed in recent years, which have already been used to manufacture the (S)-Naproxen and the (S)-Propranolol. With matched specificities such as the Lewis acidity and steric bulk, B(C₆F₅)₃ has gained accelerating attention on its application in asymmetric catalysis of Diels–Alder cycloaddition reactions, carbonyl-ene cyclization, and other various reactions, which have been demonstrated by the elegant examples from the most recent literature. Some significant progress in the reaction of indirect activation of substrates through in situ generation of numerous supramolecular catalysts from B(C₆F₅)₃ based on Lewis-acid-assisted Lewis acid (LLA) or Lewis acid assisted Brønsted acid (LBA) strategies or the reaction promoted by cooperative actions of chiral co-catalysts and B(C₆F₅)₃ which played a direct role on the activation of substrates have been demonstrated in this review. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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30 pages, 14896 KiB

Open AccessReview

Deep Eutectic Solvents as à-la-Carte Medium for Transition-Metal-Catalyzed Organic Processes

by Xavier Marset and Gabriela Guillena

Molecules 2022, 27(23), 8445; https://doi.org/10.3390/molecules27238445 - 02 Dec 2022

Cited by 14 | Viewed by 2118

Abstract

Our society is facing a tremendous challenge to become more sustainable in every sphere of life. Regarding the chemical industry, one of the most significant issues to be addressed is the use of volatile organic compounds (VOCs) as solvents because they are petrol-derived [...] Read more.

Our society is facing a tremendous challenge to become more sustainable in every sphere of life. Regarding the chemical industry, one of the most significant issues to be addressed is the use of volatile organic compounds (VOCs) as solvents because they are petrol-derived and most of them are toxic and flammable. Among the possible solutions, deep eutectic solvents (DESs) have emerged as sustainable alternatives to VOCs in organic catalyzed transformations and other fields. The advantages of these new reaction media are not only related to their more benign physical and chemical properties and, for most of them, their renewable sources but also due to the possibility of being recycled after their use, increasing the sustainability of the catalyzed process in which they are involved. However, their use as media in catalytic transformations introduces new challenges regarding the compatibility and activity of known catalysts. Therefore, designed catalysts and “à-la-carte” DESs systems have been developed to overcome this problem, to maximize the reaction outcomes and to allow the recyclability of the catalyst/media system. Over the last decade, the popularity of these solvents has steadily increased, with several examples of efficient metal-catalyzed organic transformations, showing the efficiency of the catalysts/DES system, compared to the related transformations carried out in VOCs. Additionally, due to the inherent properties of the DES, unknown transformations can be carried out using the appropriated catalyst/DES system. All these examples of sustainable catalytic processes are compiled in this review. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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17 pages, 7429 KiB

Open AccessReview

A Review on the Synthesis and Chemical Transformation of Quinazoline 3-Oxides

by Malose J. Mphahlele

Molecules 2022, 27(22), 7985; https://doi.org/10.3390/molecules27227985 - 17 Nov 2022

Cited by 4 | Viewed by 1872

Abstract

The synthesis of quinazoline 3-oxides and their derivatives has attracted considerable attention due to their reactivity as intermediates in the synthesis of quinazoline analogues and their ring-expanded derivatives. Despite this, there is no comprehensive review dedicated to the synthesis and chemical transformation of [...] Read more.

The synthesis of quinazoline 3-oxides and their derivatives has attracted considerable attention due to their reactivity as intermediates in the synthesis of quinazoline analogues and their ring-expanded derivatives. Despite this, there is no comprehensive review dedicated to the synthesis and chemical transformation of these biologically relevant azaaromatic oxides. This review aims to provide an up-to-date record of the synthesis of quinazoline 3-oxides and their chemical transformation. It is hoped that this information will help medicinal chemistry researchers to design and synthesize new derivatives or analogues to treat various diseases. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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39 pages, 13554 KiB

Open AccessReview

Synthetic Approaches to Biologically Active C-2-Substituted Benzothiazoles

by Bagrat A. Shainyan, Larisa V. Zhilitskaya and Nina O. Yarosh

Molecules 2022, 27(8), 2598; https://doi.org/10.3390/molecules27082598 - 18 Apr 2022

Cited by 8 | Viewed by 3424

Abstract

Numerous benzothiazole derivatives are used in organic synthesis, in various industrial and consumer products, and in drugs, with a wide spectrum of biological activity. As the properties of the benzothiazole moiety are strongly affected by the nature and position of substitutions, in this [...] Read more.

Numerous benzothiazole derivatives are used in organic synthesis, in various industrial and consumer products, and in drugs, with a wide spectrum of biological activity. As the properties of the benzothiazole moiety are strongly affected by the nature and position of substitutions, in this review, covering the literature from 2016, we focus on C-2-substituted benzothiazoles, including the methods of their synthesis, structural modification, reaction mechanisms, and possible pharmacological activity. The synthetic approaches to these heterocycles include both traditional multistep reactions and one-pot atom economy processes using green chemistry principles and easily available reagents. Special attention is paid to the methods of the thiazole ring closure and chemical modification by the introduction of pharmacophore groups. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry)

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