Organics

24 pages, 6726 KiB

Open AccessFeature PaperReview

A Review of the Synthetic Strategies toward Dihydropyrrolo[1,2-a]Pyrazinones

by Pieterjan Winant, Tomas Horsten, Shaiani Maria Gil de Melo, Flavio Emery and Wim Dehaen

Organics 2021, 2(2), 118-141; https://doi.org/10.3390/org2020011 - 04 Jun 2021

Cited by 5 | Viewed by 4274

Dihydropyrrolo[1,2-a]pyrazinone rings are a class of heterocycles present in a wide range of bioactive natural products and analogues thereof. As a direct result of their bioactivity, the synthesis of this privileged class of compounds has been extensively studied. This review provides an overview of these synthetic pathways. The literature is covered up until 2020 and is organized according to the specific strategies used to construct the scaffold: fusing a pyrazinone to an existing pyrrole, employing a pyrazinone-first strategy, an array of multicomponent reactions and some miscellaneous reactions. Full article

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

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11 pages, 1306 KiB

Open AccessArticle

A Sustainable Improvement of ω-Bromoalkylphosphonates Synthesis to Access Novel KuQuinones

by Mattia Forchetta, Valeria Conte, Giulia Fiorani, Pierluca Galloni and Federica Sabuzi

Organics 2021, 2(2), 107-117; https://doi.org/10.3390/org2020010 - 03 Jun 2021

Cited by 5 | Viewed by 3560

Abstract

Owing to the attractiveness of organic phosphonic acids and esters in the pharmacological field and in the functionalization of conductive metal-oxides, the research of effective synthetic protocols is pivotal. Among the others, ω-bromoalkylphosphonates are gaining particular attention because they are useful building blocks for the tailored functionalization of complex organic molecules. Hence, in this work, the optimization of Michaelis–Arbuzov reaction conditions for ω-bromoalkylphosphonates has been performed, to improve process sustainability while maintaining good yields. Synthesized ω-bromoalkylphosphonates have been successfully adopted for the synthesis of new KuQuinone phosphonate esters and, by hydrolysis, phosphonic acid KuQuinone derivatives have been obtained for the first time. Considering the high affinity with metal-oxides, KuQuinones bearing phosphonic acid terminal groups are promising candidates for biomedical and photo(electro)chemical applications. Full article

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

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9 pages, 3720 KiB

Open AccessArticle

MCR under Microwave Irradiation: Synthesis in Water of New 2-Amino-bis(2-phosphonoacetic) Acids

by Didier Villemin, Bernard Moreau and Nathalie Bar

Organics 2021, 2(2), 98-106; https://doi.org/10.3390/org2020009 - 11 May 2021

Cited by 2 | Viewed by 2960

Abstract

Novel 2-amino bis(2-phosphonoacetic) acids were prepared by microwave irradiation of a mixture of amine, glyoxylic acid and phosphorous acid. The reaction takes place with various amines including primary and secondary amines and polyamines, but this reaction is more sensitive to steric hindrance of amine than the similar Kabachnik–Fields reaction. Amino acids can be also transformed into the expected bis(2-phosphonoacetic) acids, with the exception of tryptophan, which gives a β-carboline product. Full article

(This article belongs to the Special Issue Progress in Synthesis and Applications of Phosphorus-Containing Compounds)

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14 pages, 6647 KiB

Open AccessArticle

Z,E-Isomerism in a Series of Substituted Iminophosphonates: Quantum Chemical Research

by Alexander B. Rozhenko, Andrey A. Kyrylchuk, Yuliia O. Lapinska, Yuliya V. Rassukana, Vladimir V. Trachevsky, Volodymyr V. Pirozhenko, Jerzy Leszczynski and Petro P. Onysko

Organics 2021, 2(2), 84-97; https://doi.org/10.3390/org2020008 - 23 Apr 2021

Cited by 3 | Viewed by 3500

Abstract

Esters of iminophosphonic acids (iminophosphonates, or IPs), including a fragment, >P(=O)-C=N, can be easily functionalized, for instance to aminophosphonic acids with a wide range of biological activity. Depending on the character of the substitution, the Z- or E-configuration is favorable for IPs, which in turn can influence the stereochemistry of the products of chemical transformations of IPs. While the Z,E-isomerism in IPs has been thoroughly studied by NMR spectroscopy, the factors stabilizing a definite isomer are still not clear. In the current work, density functional theory (DFT, using M06-2X functional) and ab initio spin-component–scaled second-order Møller–Plesset perturbation theory (SCS-MP2) calculations were carried out for a broad series of IPs. The calculations reproduce well a subtle balance between the preferred Z-configuration inherent for C-trifluoromethyl substituted IPs and the E-form, which is more stable for C-alkyl- or aryl-substituted IPs. The predicted trend of changing activation energy values agrees well with the recently determined experimental ΔG^≠₂₉₈ magnitudes. Depending on the substitution in the aromatic moiety, the Z/E-isomerization of N-aryl-substituted IPs proceeds via two types of close-in energy transition states. Not a single main factor but a combination of various contributions should be considered in order to explain the Z/E-isomerization equilibrium for different IPs. Full article

(This article belongs to the Special Issue Progress in Synthesis and Applications of Phosphorus-Containing Compounds)

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12 pages, 1235 KiB

Open AccessFeature PaperArticle

α-(Imino)pyridyldifluoroethyl Phosphonates: Novel Promising Building Blocks in Synthesis of Biorelevant Aminophosphonic Acids Derivatives

by Oksana M. Shavrina, Lyudmyla V. Bezgubenko, Andrii V. Bezdudny, Petro P. Onys’ko and Yuliya V. Rassukana

Organics 2021, 2(2), 72-83; https://doi.org/10.3390/org2020007 - 23 Apr 2021

Cited by 1 | Viewed by 2741

Abstract

A convenient synthetic approach to previously unknown NH-iminophosphonates bearing 2-, 3-, and 4-pyridyldifluoromethyl groups at the imine carbon atom was developed. The synthetic potential of these novel building blocks was demonstrated by their conversion into highly functionalized acyclic and heterocyclic aminophosphonates and phosphonic acids combining in their structure biorelevant aminophosphonic fragment, difluoromethyl group, and pyridyl, piperidyl, thiazolidin-4-one, or thiazidinan-4-one heterocyclic moieties in a single molecular platform. Full article

(This article belongs to the Special Issue Progress in Synthesis and Applications of Phosphorus-Containing Compounds)

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Organics, Volume 2, Issue 2 (June 2021) – 5 articles

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