Organics

18 pages, 3783 KiB

Open AccessArticle

On the Mechanism of the Synthesis of Nitrofunctionalised Δ²-Pyrazolines via [3+2] Cycloaddition Reactions between α-EWG-Activated Nitroethenes and Nitrylimine TAC Systems

by Agnieszka Fryźlewicz, Aleksandra Olszewska, Karolina Zawadzińska, Przemysław Woliński, Karolina Kula, Agnieszka Kącka-Zych, Agnieszka Łapczuk-Krygier and Radomir Jasiński

Organics 2022, 3(1), 59-76; https://doi.org/10.3390/org3010004 - 01 Mar 2022

Cited by 5 | Viewed by 2300

Abstract

We investigated the reactivity of different substituted nitrylimine-type three atom components (TACs) in [3+2] cycloaddition (32CAs) reactions with electrophilically activated nitroethenes within molecular electron density theory (MEDT). In parallel research, the molecular mechanism of the considered transformation was examined through analysis of all [...] Read more.

We investigated the reactivity of different substituted nitrylimine-type three atom components (TACs) in [3+2] cycloaddition (32CAs) reactions with electrophilically activated nitroethenes within molecular electron density theory (MEDT). In parallel research, the molecular mechanism of the considered transformation was examined through analysis of all possible reaction channels and full optimization of all critical structures. In particular, the existence of zwitterionic intermediates on reaction paths was verified. On the basis of the bonding evolution theory (BET), the mechanism of the 32CA reaction between C,N-diphenylnitrylimine and (E)-2-phenyl-1-cyano-1-nitroethene should be treated as a one-step two-stage mechanism. Full article

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21 pages, 27734 KiB

Open AccessArticle

¹³C NMR Spectroscopic Studies of Intra- and Intermolecular Interactions of Amino Acid Derivatives and Peptide Derivatives in Solutions

by Yoshikazu Hiraga, Saori Chaki, Yuri Uyama, Ryosuke Hoshide, Takumi Karaki, Daisuke Nagata, Kanji Yoshimoto and Satomi Niwayama

Organics 2022, 3(1), 38-58; https://doi.org/10.3390/org3010003 - 09 Feb 2022

Viewed by 3389

Abstract

¹³C NMR spectroscopic investigations were conducted for various amino acid derivatives and peptides. It was observed that ¹³C NMR chemical shifts of the carbonyl carbons are correlated with the solvent polarities, but the extent depends on the structures. The size of [...] Read more.

¹³C NMR spectroscopic investigations were conducted for various amino acid derivatives and peptides. It was observed that ¹³C NMR chemical shifts of the carbonyl carbons are correlated with the solvent polarities, but the extent depends on the structures. The size of the functional groups and inter- and intra-molecular hydrogen bonding appear to be the major contributors for this tendency. Full article

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

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16 pages, 3556 KiB

Open AccessArticle

De Novo Synthesis of Bacteriochlorins Bearing Four Trideuteriomethyl Groups

by Haoyu Jing, Qun Tang, David F. Bocian and Jonathan S. Lindsey

Organics 2022, 3(1), 22-37; https://doi.org/10.3390/org3010002 - 07 Feb 2022

Cited by 3 | Viewed by 2293

Abstract

Site-specific introduction of isotopes in tetrapyrrole macrocycles provides the foundation for probing physicochemical features germane to photosynthetic energy-transduction processes, but has chiefly been done with porphyrins rather than the more biologically relevant hydroporphyrin analogues of native photosynthetic pigments. A prior study incorporated pairwise [...] Read more.

Site-specific introduction of isotopes in tetrapyrrole macrocycles provides the foundation for probing physicochemical features germane to photosynthetic energy-transduction processes, but has chiefly been done with porphyrins rather than the more biologically relevant hydroporphyrin analogues of native photosynthetic pigments. A prior study incorporated pairwise ¹³C or ¹⁵N atoms in the skeleton of a bacteriochlorin containing a gem-dimethyl group in each pyrroline ring. Here, a complementary effort is reported that installs deuterium atoms in substituents at the perimeter of a bacteriochlorin. Thus, perdeuteriated 3-methyl-2,4-pentanedione was converted in an 8-step synthesis via the intermediacy of tert-butyl 5-formyl-3,4-bis(trideuteriomethyl)pyrrole-2-carboxylate to the 2,3,12,13-tetrakis(trideuteriomethyl)-8,8,18,18-tetramethylbacteriochlorin (BC-2). The fidelity of isotope substitution was maintained throughout the synthesis. Resonance Raman spectroscopy of the copper chelate (CuBC-2) revealed that addition of the four β-pyrrolic substituents alone is not sufficient to account for the vibronic complexity observed for the copper chelate of bacteriochlorophyll a (CuBChl a). The increased vibronic activity exhibited by the natural pigments and CuBChl a must arise from the increased structural complexity of the macrocycle. Full article

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

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21 pages, 7259 KiB

Open AccessReview

Recent Applications of Pd-Catalyzed Suzuki–Miyaura and Buchwald–Hartwig Couplings in Pharmaceutical Process Chemistry

by Balaram S. Takale, Fan-Yi Kong and Ruchita R. Thakore

Organics 2022, 3(1), 1-21; https://doi.org/10.3390/org3010001 - 18 Jan 2022

Cited by 15 | Viewed by 6548

Abstract

Cross-coupling reactions have changed the way complex molecules are synthesized. In particular, Suzuki–Miyaura and Buchwald–Hartwig amination reactions have given opportunities to elegantly make pharmaceutical ingredients. Indeed, these reactions are at the forefront of both the stages of drug development, medicinal chemistry, and process [...] Read more.

Cross-coupling reactions have changed the way complex molecules are synthesized. In particular, Suzuki–Miyaura and Buchwald–Hartwig amination reactions have given opportunities to elegantly make pharmaceutical ingredients. Indeed, these reactions are at the forefront of both the stages of drug development, medicinal chemistry, and process chemistry. On the one hand, these reactions have given medicinal chemists a resource to derivatize the core compound to arrive at scaffold rapidly. On the other hand, these cross couplings have offered the process chemists a smart tool to synthesize the development candidates safely, quickly, and efficiently. Generally, the application of cross-coupling reactions is broad. This review will specifically focus on their real (pharma) world applications in large-scale synthesis appearing in the last three years. Full article

(This article belongs to the Special Issue New Reactions and Strategies for Natural Product Synthesis)

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Organics, Volume 3, Issue 1 (March 2022) – 4 articles

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