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14 pages, 1607 KiB

Open AccessArticle

Tethered Blatter Radical for Molecular Grafting: Synthesis of 6-Hydroxyhexyloxy, Hydroxymethyl, and Bis(hydroxymethyl) Derivatives and Their Functionalization

by Szymon Kapuściński, Bindushree Anand, Paulina Bartos, Jose M. Garcia Fernandez and Piotr Kaszyński

Molecules 2022, 27(4), 1176; https://doi.org/10.3390/molecules27041176 - 9 Feb 2022

Cited by 3 | Viewed by 2420

Abstract

Synthetic access to 7-CF₃-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl radicals containing 4-(6-hydroxyhexyloxy)phenyl, 4-hydroxymethylphenyl or 3,5-bis(hydroxymethyl)phenyl groups at the C(3) position and their conversion to tosylates and phosphates are described. The tosylates were used to obtain disulfides and an azide with good yields. The Blatter [...] Read more.

Synthetic access to 7-CF₃-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl radicals containing 4-(6-hydroxyhexyloxy)phenyl, 4-hydroxymethylphenyl or 3,5-bis(hydroxymethyl)phenyl groups at the C(3) position and their conversion to tosylates and phosphates are described. The tosylates were used to obtain disulfides and an azide with good yields. The Blatter radical containing the azido group underwent a copper(I)-catalyzed azide–alkyne cycloaddition with phenylacetylene under mild conditions, giving the [1,2,3]triazole product in 84% yield. This indicates the suitability of the azido derivative for grafting Blatter radical onto other molecular objects via the CuAAC “click” reaction. The presented derivatives are promising for accessing surfaces and macromolecules spin-labeled with the Blatter radical. Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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21 pages, 4412 KiB

Open AccessArticle

An Efficient Approach to 2-CF₃-Indoles Based on ortho-Nitrobenzaldehydes

by Vasiliy M. Muzalevskiy, Zoia A. Sizova, Vladimir T. Abaev and Valentine G. Nenajdenko

Molecules 2021, 26(23), 7365; https://doi.org/10.3390/molecules26237365 - 4 Dec 2021

Cited by 6 | Viewed by 2314

Abstract

The catalytic olefination reaction of 2-nitrobenzaldehydes with CF₃CCl₃ afforded stereoselectively trifluoromethylated ortho-nitrostyrenes in up to 88% yield. The reaction of these alkenes with pyrrolidine permits preparation of α-CF₃-β-(2-nitroaryl) enamines. Subsequent one pot reduction of nitro-group by Fe-AcOH-H [...] Read more.

The catalytic olefination reaction of 2-nitrobenzaldehydes with CF₃CCl₃ afforded stereoselectively trifluoromethylated ortho-nitrostyrenes in up to 88% yield. The reaction of these alkenes with pyrrolidine permits preparation of α-CF₃-β-(2-nitroaryl) enamines. Subsequent one pot reduction of nitro-group by Fe-AcOH-H₂O system initiated intramolecular cyclization to afford 2-CF₃-indoles. Target products can be prepared in up to 85% yields. Broad synthetic scope of the reaction was shown as well as some followed up transformations of 2- CF₃-indole. Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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18 pages, 4642 KiB

Open AccessArticle

Radical and Ionic Mechanisms in Rearrangements of o-Tolyl Aryl Ethers and Amines Initiated by the Grubbs–Stoltz Reagent, Et₃SiH/KO^tBu

by Krystian Kolodziejczak, Alexander J. Stewart, Tell Tuttle and John A. Murphy

Molecules 2021, 26(22), 6879; https://doi.org/10.3390/molecules26226879 - 15 Nov 2021

Cited by 4 | Viewed by 3168

Abstract

Rearrangements of o-tolyl aryl ethers, amines, and sulfides with the Grubbs–Stoltz reagent (Et₃SiH + KO^tBu) were recently announced, in which the ethers were converted to o-hydroxydiarylmethanes, while the (o-tol)(Ar)NH amines were transformed into dihydroacridines. Radical [...] Read more.

Rearrangements of o-tolyl aryl ethers, amines, and sulfides with the Grubbs–Stoltz reagent (Et₃SiH + KO^tBu) were recently announced, in which the ethers were converted to o-hydroxydiarylmethanes, while the (o-tol)(Ar)NH amines were transformed into dihydroacridines. Radical mechanisms were proposed, based on prior evidence for triethylsilyl radicals in this reagent system. A detailed computational investigation of the rearrangements of the aryl tolyl ethers now instead supports an anionic Truce–Smiles rearrangement, where the initial benzyl anion can be formed by either of two pathways: (i) direct deprotonation of the tolyl methyl group under basic conditions or (ii) electron transfer to an initially formed benzyl radical. By contrast, the rearrangements of o-tolyl aryl amines depend on the nature of the amine. Secondary amines undergo deprotonation of the N-H followed by a radical rearrangement, to form dihydroacridines, while tertiary amines form both dihydroacridines and diarylmethanes through radical and/or anionic pathways. Overall, this study highlights the competition between the reactive intermediates formed by the Et₃SiH/KO^tBu system. Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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14 pages, 3588 KiB

Open AccessArticle

A DFT Study on the Molecular Mechanism of Additions of Electrophilic and Nucleophilic Carbenes to Non-Enolizable Cycloaliphatic Thioketones

by Grzegorz Mlostoń, Karolina Kula and Radomir Jasiński

Molecules 2021, 26(18), 5562; https://doi.org/10.3390/molecules26185562 - 13 Sep 2021

Cited by 8 | Viewed by 2411

Abstract

The molecular mechanisms of addition of dihalocarbenes and dimethoxycarbene to thioketones derived from 2,2,4,4-tetrmethylcyclobutane-1,3-dione were examined on the basis of the DFT wb97xd/6-311g(d,p)(PCM) calculations. Obtained results demonstrated that the examined processes exhibit polar nature and in the case of electrophilic dichloro-, and dibromocarbenes [...] Read more.

The molecular mechanisms of addition of dihalocarbenes and dimethoxycarbene to thioketones derived from 2,2,4,4-tetrmethylcyclobutane-1,3-dione were examined on the basis of the DFT wb97xd/6-311g(d,p)(PCM) calculations. Obtained results demonstrated that the examined processes exhibit polar nature and in the case of electrophilic dichloro-, and dibromocarbenes are initiated by the attack of carbene species onto the sulfur atom of the C=S group. Remarkably, reactions involving more electrophilic carbenes (dichloro-, and dibromocarbene) proceeds via stepwise mechanism involving thiocarbonyl ylide as a transient intermediate. In contrast, analogous reactions with nucleophilic dimethoxycarbene occur via a single step reaction, which can be considered as the [2 + 1] cycloaddition reaction initiated by the attack onto the C=S bond. A computational study showed that difluorocarbene tends to react as a nucleophilic species and resembles rather dimethoxycarbene and not typical dihalocarbene species. Significantly higher reactivity of the thioketone unit in comparison to the ketone group, both present in 3-thioxo-2,2,4,4-tetramthylcyclobutanone molecule, was rationalized in the light of DFT computational study. Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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18 pages, 2676 KiB

Open AccessArticle

Oxidative C-H/C-H Coupling of Dipyrromethanes with Azines by TiO₂-Based Photocatalytic System. Synthesis of New BODIPY Dyes and Their Photophysical and Electrochemical Properties

by Maria A. Trestsova, Irina A. Utepova, Oleg N. Chupakhin, Maksim V. Semenov, Dmitry N. Pevtsov, Lyubov M. Nikolenko, Sergey A. Tovstun, Anna V. Gadomska, Alexander V. Shchepochkin, Gregory A. Kim, Vladimir F. Razumov, Irina B. Dorosheva and Andrey A. Rempel

Molecules 2021, 26(18), 5549; https://doi.org/10.3390/molecules26185549 - 13 Sep 2021

Cited by 5 | Viewed by 2405

Abstract

Oxidative C-H/C-H coupling reactions of dipyrromethanes with azines in the presence of a heterophase oxidative photocatalytic system (O₂/TiO₂/visible light irradiation) were carried out. As a result of cyclization of obtained compounds with boron trifluoride etherate, new hetaryl-containing derivatives of [...] Read more.

Oxidative C-H/C-H coupling reactions of dipyrromethanes with azines in the presence of a heterophase oxidative photocatalytic system (O₂/TiO₂/visible light irradiation) were carried out. As a result of cyclization of obtained compounds with boron trifluoride etherate, new hetaryl-containing derivatives of 4,4-difluoro-4-boron-3a,4a-diaza-s-indacene were synthesized. For the obtained compounds, absorption and luminescence spectra, quantum yields of luminescence as well as cyclic volt-amperograms were measured. Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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13 pages, 1355 KiB

Open AccessCommunication

Doubly Decarboxylative Synthesis of 4-(Pyridylmethyl)chroman-2-ones and 2-(Pyridylmethyl)chroman-4-ones under Mild Reaction Conditions

by Jan Bojanowski and Anna Albrecht

Molecules 2021, 26(15), 4689; https://doi.org/10.3390/molecules26154689 - 3 Aug 2021

Cited by 4 | Viewed by 2364

Abstract

The doubly decarboxylative Michael–type addition of pyridylacetic acid to chromone-3-carboxylic acids or coumarin-3-carboxylic acids has been developed. This protocol has been realized under Brønsted base catalysis, providing biologically interesting 4-(pyridylmethyl)chroman-2-ones and 2-(pyridylmethyl)chroman-4-ones in good or very good yields. The decarboxylative reaction pathway has [...] Read more.

The doubly decarboxylative Michael–type addition of pyridylacetic acid to chromone-3-carboxylic acids or coumarin-3-carboxylic acids has been developed. This protocol has been realized under Brønsted base catalysis, providing biologically interesting 4-(pyridylmethyl)chroman-2-ones and 2-(pyridylmethyl)chroman-4-ones in good or very good yields. The decarboxylative reaction pathway has been confirmed by mechanistic studies. Moreover, attempts to develop an enantioselective variant of the cascade are also described. Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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15 pages, 1540 KiB

Open AccessCommunication

Synthesis of (Het)aryl 2-(2-hydroxyaryl)cyclopropyl Ketones

by Alexander A. Fadeev, Alexey O. Chagarovskiy, Anton S. Makarov, Irina I. Levina, Olga A. Ivanova, Maxim G. Uchuskin and Igor V. Trushkov

Molecules 2020, 25(23), 5748; https://doi.org/10.3390/molecules25235748 - 5 Dec 2020

Cited by 3 | Viewed by 3608

Abstract

A simple general method for the synthesis of 1-acyl-2-(ortho-hydroxyaryl)cyclopropanes, which belong to the donor–acceptor cyclopropane family, has been developed. This method, based on the Corey–Chaykovsky cyclopropanation of 2-hydroxychalcones, allows for the preparation of a large diversity of hydroxy-substituted cyclopropanes, which can [...] Read more.

A simple general method for the synthesis of 1-acyl-2-(ortho-hydroxyaryl)cyclopropanes, which belong to the donor–acceptor cyclopropane family, has been developed. This method, based on the Corey–Chaykovsky cyclopropanation of 2-hydroxychalcones, allows for the preparation of a large diversity of hydroxy-substituted cyclopropanes, which can serve as promising building blocks for the synthesis of various bioactive compounds. Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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Review

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25 pages, 6151 KiB

Open AccessReview

Triptycene Derivatives: From Their Synthesis to Their Unique Properties

by Mateusz Woźny, Adam Mames and Tomasz Ratajczyk

Molecules 2022, 27(1), 250; https://doi.org/10.3390/molecules27010250 - 31 Dec 2021

Cited by 17 | Viewed by 6533

Abstract

Since the first preparation of triptycene, great progress has been made with respect to its synthesis and the understanding of its properties. Interest in triptycene-based systems is intense; in recent years, advances in the synthetic methodology and properties of new triptycenes have been [...] Read more.

Since the first preparation of triptycene, great progress has been made with respect to its synthesis and the understanding of its properties. Interest in triptycene-based systems is intense; in recent years, advances in the synthetic methodology and properties of new triptycenes have been reported by researchers from various fields of science. Here, an account of these new developments is given and placed in reference to earlier pivotal works that underpin the field. First, we discuss new approaches to the synthesis of new triptycenes. Progress in the regioselective synthesis of sterically demanding systems is discussed. The application of triptycenes in catalysis is also presented. Next, progress in the understanding of the relations between triptycene structures and their properties is discussed. The unique properties of triptycenes in the liquid and solid states are elaborated. Unique interactions, which involve triptycene molecular scaffolds, are presented. Molecular interactions within a triptycene unit, as well as between triptycenes or triptycenes and other molecules, are also evaluated. In particular, the summary of the synthesis and useful features will be helpful to researchers who are using triptycenes as building blocks in the chemical and materials sciences. Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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30 pages, 13506 KiB

Open AccessReview

Electron-Deficient Acetylenes as Three-Modal Adjuvants in S_N^H Reaction of Pyridinoids with Phosphorus Nucleophiles

by Boris A. Trofimov, Pavel A. Volkov and Anton A. Telezhkin

Molecules 2021, 26(22), 6824; https://doi.org/10.3390/molecules26226824 - 11 Nov 2021

Cited by 10 | Viewed by 2097

Abstract

Publications covering a new easy metal-free functionalization of pyridinoids (pyridines, quinolines, isoquinolines, acridine) under the action of the system of electron-deficient acetylenes (acetylenecarboxylic acid esters, acylacetylenes)/P-nucleophiles (phosphine chalcogenides, H-phosphonates) are reviewed. Special attention is focused on a S_N^H [...] Read more.

Publications covering a new easy metal-free functionalization of pyridinoids (pyridines, quinolines, isoquinolines, acridine) under the action of the system of electron-deficient acetylenes (acetylenecarboxylic acid esters, acylacetylenes)/P-nucleophiles (phosphine chalcogenides, H-phosphonates) are reviewed. Special attention is focused on a S_N^H reaction of the regioselective cross-coupling of pyridines with secondary phosphine chalcogenides triggered by acylacetylenes to give 4-chalcogenophosphorylpyridines. In these processes, acetylenes act as three-modal adjuvants (i) activating the pyridine ring towards P-nucleophiles, (ii) deprotonating the P-H bond and (iii) facilitating the nucleophilic addition of the P-centered anion to a heterocyclic moiety followed by the release of the selectively reduced acetylenes (E-alkenes). Full article

(This article belongs to the Special Issue Advances in Organic Synthesis: A Theme Issue in Honor of Professor Mieczysław Mąkosza)

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