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1 pages, 188 KiB

Open AccessAbstract

Pd-Catalyzed Cycloaddition of Bicyclic Aziridine with Isocyanates

by Mariana Crespo Monteiro, Carlos A. M. Afonso and Filipa Siopa

Med. Sci. Forum 2022, 14(1), 97; https://doi.org/10.3390/ECMC2022-13424 - 1 Nov 2022

Viewed by 915

Nitrogen-containing heterocycles can have several applications in the pharmaceutical industry since they contain a wide spectrum of biological activities. Imidazolidinones have shown activity against leukemia, lung cancer, and metabolic disorders. These cyclic urea frameworks can be obtained through transition-metal-catalyzed intermolecular cycloaddition using an aziridine moiety as the starting material. These reactions often provide effective one-step procedures that result in heterocyclic derivatives that are challenging to access through conventional approaches. We have previously described the photoreaction of butyl pyridinium salt with the corresponding bicyclic aziridine in continuous flow. Additionally, we reported that the palladium-catalyzed ring opening of bicyclic aziridines with active methylenes exhibited a new S_N2’ selectivity. In this study, the reaction between bicyclic aziridines and several isocyanates, in the presence of Pd(0)-catalyst is presented. The reactions proceed through ring opening of the aziridine moiety, with the formation of the π-allylpalladium complex, followed by cyclization via nucleophilic addition of nitrogen to the isocyanate, affording regioselectively imidazolidinones. Full article

(This article belongs to the Proceedings of The 8th International Electronic Conference on Medicinal Chemistry)

44 pages, 13246 KiB

Open AccessReview

Recent Developments in Stereoselective Reactions of Sulfonium Ylides

by Mukulesh Mondal, Sophie Connolly, Shi Chen, Shubhanjan Mitra and Nessan J. Kerrigan

Organics 2022, 3(3), 320-363; https://doi.org/10.3390/org3030024 - 15 Sep 2022

Cited by 19 | Viewed by 8294

Abstract

This review describes advances in the literature since the mid-1990s in the area of reactions of sulfonium ylide chemistry, with particular attention paid to stereoselective examples. Although the chemistry of sulfonium ylides was first popularized and applied in a substantial way in the 1960s, there has been sustained interest in the chemistry of sulfonium ylides since then. Many new ways of exploiting sulfonium ylides in productive stereoselective methodologies have emerged, often taking advantage of advances in organocatalysis and transition metal catalysis, to access stereodefined structurally complex motifs. The development of many different chiral sulfides over the last 20–30 years has also played a role in accelerating their study in a variety of reaction settings. In general, formal cycloaddition reactions ([2 + 1] and [4 + 1]) of sulfonium ylides follow a similar mechanistic pathway: initial addition of the nucleophilic ylide carbanion to an electrophile to form a zwitterionic betaine intermediate, followed by cyclization of the zwitterionic intermediate to afford the desired three-membered cyclic product (e.g., epoxide, cyclopropane, or aziridine), five-membered monocyclic (e.g., oxazolidinone), or fused bicyclic product (e.g., benzofuran, indoline). Full article

(This article belongs to the Collection Advanced Research Papers in Organics)

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5 pages, 1172 KiB

Open AccessShort Note

(1R,4S,5S)-5-((3-Hydroxypropyl)amino)-4-((1-methyl-1H-tetrazol-5-yl)thio)cyclopent-2-en-1-ol

by Milene A. G. Fortunato, Filipa Siopa and Carlos A. M. Afonso

Molbank 2021, 2021(2), M1199; https://doi.org/10.3390/M1199 - 1 Apr 2021

Cited by 2 | Viewed by 3935

Abstract

Using environmentally friendly conditions, the nucleophilic ring-opening reaction of 6-azabicyclo[3.1.0]hex-3-en-2-ol with 1-methyl-1H-tetrazole-5-thiol provided a novel thiol-incorporated aminocyclopentitol, (1R,4S,5S)-5-((3-hydroxypropyl)amino)-4-((1-methyl-1H-tetrazol-5-yl)thio)cyclopent-2-en-1-ol, in excellent yield (95%). The newly synthesized compound was analyzed and characterized via ¹H, ¹³C-NMR, HSQC, and mass spectral data. Full article

(This article belongs to the Special Issue Nitrogen-Containing Molecules: Natural and Synthetic Products Including Coordination Compounds)

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9 pages, 6354 KiB

Open AccessBenchmark

Process Intensification for the Synthesis of 6-Allyl-6-azabicyclo[3.1.0]hex-3-en-2-ol from 1-Allylpyridinium Salt Using a Continuous UV-Light Photoflow Approach

by Milene A. G. Fortunato, Chi-Phong Ly, Filipa Siopa and Carlos A. M. Afonso

Methods Protoc. 2019, 2(3), 67; https://doi.org/10.3390/mps2030067 - 5 Aug 2019

Cited by 6 | Viewed by 3810

Abstract

A new home-made UV photochemical reactor (95 cm of irradiation zone) consisting of a 12 parallel quartz tubes flow reactor, PQT6 (95 cm under irradiation and an internal diameter of 0.6 cm) was assembled to perform photochemical transformations in continuous-flow. PQT6 was evaluated for the photoreaction of 1-allylpyridinium bromide (1a) to 6-allyl-6-azabicyclo[3.1.0]hex-3-en-2-ol (2a), in a continuous process. This technology provides reduced reaction times, continuous production of 2a, and a productivity of 129 mg h⁻¹, corresponding to 1.94 g of isolated 2a after 15 h of irradiation. Full article

(This article belongs to the Collection Green Chemistry)

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29 pages, 32575 KiB

Open AccessFeature PaperReview

Recent Developments in Vinylsulfonium and Vinylsulfoxonium Salt Chemistry

by Mukulesh Mondal, Shi Chen and Nessan J. Kerrigan

Molecules 2018, 23(4), 738; https://doi.org/10.3390/molecules23040738 - 23 Mar 2018

Cited by 57 | Viewed by 8923

Abstract

This review describes advances in the literature since 2000 in the area of reactions of vinylsulfonium and vinylsulfoxonium salts, with a particular emphasis on stereoselective examples. Although the chemistry of vinylsulfonium salts was first explored back in the 1950s, and that of vinylsulfoxonium salts in the early 1970s, there has been renewed interest in these compounds since the turn of the century. This has been largely due to an increased appreciation for the many synthetic possibilities associated with these valuable electrophiles. The development of improved routes to vinylsulfonium salts allowing for their in situ generation has played a part in accelerating their study. In general, reactions of the two sulfur salt classes follow a similar mechanistic pathway: initial conjugate addition of a nucleophile to the β-position, followed by protonation of an ylide intermediate, and cyclization of tethered anion to afford monocyclic or bicyclic product (e.g., cyclopropane, aziridine, oxazole, oxazolidinone, γ-lactam or γ-lactone). Alternatively, reactions involve formation of an ylide intermediate followed by intramolecular Johnson-Corey-Chaykovsky reaction (epoxidation or cyclopropanation), and subsequent cyclization to afford the desired bicyclic product (e.g., fused bicyclic epoxide or cyclopropane). Full article

(This article belongs to the Section Organic Chemistry)

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9 pages, 356 KiB

Open AccessShort Note

2-(5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)-6-(4-nitrophenyl)-4-phenyl-1,3-diazabicyclo[3.1.0]hex-3-ene

by Fereshteh Albooye and Hamzeh Kiyani

Molbank 2013, 2013(3), M806; https://doi.org/10.3390/M806 - 29 Jul 2013

Cited by 2 | Viewed by 7077

Abstract

As a consequence of one-pot, three-component reaction of trans-2-benzoyl-3-(4-nitrophenyl)aziridine with 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde and ammonium acetate, 2-(5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)-6-(4-nitrophenyl)-4-phenyl-1,3-diazabicyclo[3.1.0]hex-3-ene was achieved in good yield. The desired photochromic compound display interesting photochromic behavior in the crystalline and solution phase. The structure of the [...] Read more.

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Graphical abstract

5 pages, 190 KiB

Open AccessShort Note

2-(4-Diethoxymethylphenyl)-6-(4-nitrophenyl)-4-phenyl-1,3-diazabicyclo[3.1.0]hex-3-ene

by Hamzeh Kiyani

Molbank 2012, 2012(4), M780; https://doi.org/10.3390/M780 - 28 Sep 2012

Cited by 3 | Viewed by 4088

Abstract

The photochromic compound was obtained from 4-diethoxymethyl-benzaldehyde and trans-2-benzoyl-3-(4-nitrophenyl)aziridine via a three component reaction. The structure of this compound was characterized by elemental analysis, ¹H-NMR, ¹³C-NMR and UV-Visible spectral data. Full article

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