Stabilizing the Boat Conformation of Piperazines Coordinated to Iron(II): <i>iso</i>‐Butyl Substituents Lead to Robust Oxidation Catalysts via Hyperconjugation

Ostermeier, Marc; Limberg, Christian; Herwig, Christian; Ziemer, Burkhard

doi:10.1002/zaac.200900275

Cited by 12 publications

(6 citation statements)

References 37 publications

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“…With these features they represent interesting potential ligands. [20][21][22] Cysteine, however, has only been employed rarely in such syntheses, as the thiol functions cause problems, due to thiol oxidation resulting in disulfide formation. [23] Hence, in various attempts to prepare cyclo-l-Cys-l-Cys corresponding cystine derivatives were obtained.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of a Chiral, Polydentate Ligand System Setting Out from L‐Cysteine and First Nickel Complexes Thereof

Warner

Limberg

Mebs

2013

Zeitschrift anorg allge chemie

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Setting out from protected l-cysteine a 2,5-diketopiperazine V can be synthesized, the reduction of which with NaBH 4 /TiCl 4 leads to (6R,8aR)-7-methyl-6-(sulfanylmethyl)-thiazolidine [3,4-a] piperazine, L 1 H as well as N,NЈ-dimethyl-(2R,5R)-bis(sulfanylmethyl) piperazine, L 2 H 2 , which were separated and characterized. L 2 H 2 can be obtained selectively, if V is reduced by NaBH 4 /TiCl 4 in the presence of DIEA·HCl, and it represents a precursor for a novel, chiral ligand, as after deprotonation it provides two thiolato and two amino donor * Prof. Dr. C. Limberg E-Mail: christian.limberg@chemie.hu-berlin.de [a] 1577 functions for the coordination of a metal atom. Deprotonation of L 1 H and L 2 H 2 with NaOMe followed by treatment with NiBr 2 (dme) led to the isolation of the dimeric complexes [L 1 NiBr] 2 (1) and [L 2 Ni] 2 (2), respectively. Both were fully characterized, and cyclic voltammetry indicated the possibility of Ni II Ǟ Ni III oxidations for complex 2. 2 can be regarded as a structural model for the A clusters of the acetyl coenzyme A synthase. thus electronically resembles cysteinate a lot. It even exhibits chirality -a common feature of enzymatic reaction pockets, in the simulation of which we have been interested in recent years. [17,18] Results and DiscussionThe structure of peptides is often simulated by 2,5-dioxypiperazines. These dipetides are the smallest possible cyclopeptides and they can be synthesized starting from natural amino acids. A facile and elegant synthesis for cyclo-peptides has been developed 1968 by D. E. Nitecki et al. setting out from amino acids like phenylalanine, alanine, leucine, valine or threonine. [19] In a first step an optically pure Boc-dipeptide methyl ester (I) is generated from an N-boc protected amino acid and an O-methylated amino acid in a condensation reaction (see AA 1 and AA 2 in Scheme 1). After cleavage of the boc protection group under acidic conditions the resulting dipeptide ester re-Scheme 1. Synthesis of cyclodipeptides (DCC = N,N'-dicyclo-hexylcarbodiimide).

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Section: Resultsmentioning

confidence: 99%

Synthesis of a Chiral, Polydentate Ligand System Setting Out from L‐Cysteine and First Nickel Complexes Thereof

Warner

Limberg

Mebs

2013

Zeitschrift anorg allge chemie

Self Cite

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“…Despite this, a limited number of sources has explored other routes, such as the formation of an hydroperoxo-Fe(porphyrin) complexes in P45models [55][56][57][58][59], in non-porphyrinic Fe catalysts [60][61][62][63] and also on Mn catalysts [64][65][66][67]. Nevertheless, the activity of such hydroperoxo species towards epoxidation reactions has been questioned by Shaik and co-workers [68], at least in models of cytochrome P450.…”

Section: Insights On the Reaction Mechanismmentioning

confidence: 99%

Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

Teixeira

Cordeiro

2016

Catalysts

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Abstract:The importance of epoxides as synthetic intermediates in a number of highly added-value chemicals, as well as the search for novel and more sustainable chemical processes have brought considerable attention to the catalytic activity of manganese and iron complexes towards the epoxidation of alkenes using non-toxic terminal oxidants. Particular attention has been given to Mn(salen) and Fe(porphyrin) catalysts. While the former attain remarkable enantioselectivity towards the epoxidation of cis-alkenes, the latter also serve as an important model for the behavior of cytochrome P450, thus allowing the exploration of complex biological processes. In this review, a systematic survey of the bibliographical data for the theoretical studies on Mn-and Fe-catalyzed epoxidations is presented. The most interesting patterns and trends are reported and finally analyzed using an evaluation framework similar to the SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis performed in enterprise media, with the ultimate aim to provide an overview of current trends and areas for future exploration.

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“…Additional references cited within the Supporting Information. [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]…”

Section: Glucose Uptake Assaymentioning

confidence: 99%

Peroxisome Proliferator Activated Receptor‐γ Agonistic Compounds from the Jellyfish‐Derived Fungus Cladosporium oxysporum

Luo

Wang

et al. 2023

Chemistry & Biodiversity

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In our search for peroxisome proliferator‐activated receptor (PPAR) agonists, five undescribed compounds, namely two acyclic diterpenes (1 and 2; cladopsol A and cladopsol B), two sesquiterpenes (3 and 4; cladopsol C and cladopsol D), and one C21‐ecdysteroid (5; cladopsol E), and 15 known compounds were isolated from the jellyfish‐derived fungus—Cladosporium oxysporum. The structures of the undescribed compounds were defined using UV, NMR, HRESIMS, and electronic circular dichroism (ECD) spectroscopy and a modified Mosher’s method. Luciferase reporter assay and docking analysis suggested that cladopsol B may function as a PPAR‐g partial agonist with a potential antidiabetic lead which may evade the side effects of full agonists. Moreover, cladopsol B stimulated glucose uptake in HepG2 cells with an efficacy comparable to that of rosiglitazone, but with less side effect induced by lipid accumulation in 3T3‐L1 cells. Therefore, cladopsol B could serve as a molecular skeleton in a study of advanced antidiabetic lead with less side effect.

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Stabilizing the Boat Conformation of Piperazines Coordinated to Iron(II): iso‐Butyl Substituents Lead to Robust Oxidation Catalysts via Hyperconjugation

Cited by 12 publications

References 37 publications

Synthesis of a Chiral, Polydentate Ligand System Setting Out from L‐Cysteine and First Nickel Complexes Thereof

Synthesis of a Chiral, Polydentate Ligand System Setting Out from L‐Cysteine and First Nickel Complexes Thereof

Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

Peroxisome Proliferator Activated Receptor‐γ Agonistic Compounds from the Jellyfish‐Derived Fungus Cladosporium oxysporum

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