3042-22-6Relevant academic research and scientific papers
HEXACARBONYLMOLYBDENUM- OR NONACARBONYLDIIRON-INDUCED REACTION OF 1,3-OXAZEPINE RING SYSTEM. EVIDENCE FOR THE VALENCE ISOMERIZATION BETWEEN 1,3-OXAZEPINE AND PYRIDINE-2,3-OXIDE
Nitta, Makoto,Kobayashi, Tomoshige
, p. 877 - 880 (1985)
Upon treatment with or , phenyl-substituted 1,3-oxazepines undergo the C-2-O and C-7-O bond cleavage to give pyridine and pyrrole derivatives via a coordinated pyridine-2,3-oxide.
Increase of Direct C-C Coupling Reaction Yield by Identifying Structural and Electronic Properties of High-Spin Iron Tetra-azamacrocyclic Complexes
Brewer, Samantha M.,Wilson, Kevin R.,Jones, Donald G.,Reinheimer, Eric W.,Archibald, Stephen J.,Prior, Timothy J.,Ayala, Megan A.,Foster, Alexandria L.,Hubin, Timothy J.,Green, Kayla N.
, p. 8890 - 8902 (2018)
Macrocyclic ligands have been explored extensively as scaffolds for transition metal catalysts for oxygen and hydrogen atom transfer reactions. C-C reactions facilitated using earth abundant metals bound to macrocyclic ligands have not been well-understood but could be a green alternative to replacing the current expensive and toxic precious metal systems most commonly used for these processes. Therefore, the yields from direct Suzuki-Miyaura C-C coupling of phenylboronic acid and pyrrole to produce 2-phenylpyrrole facilitated by eight high-spin iron complexes ([Fe3+L1(Cl)2]+, [Fe3+L4(Cl)2]+, [Fe2+L5(Cl)]+, [Fe2+L6(Cl)2], [Fe3+L7(Cl)2]+, [Fe3+L8(Cl)2]+, [Fe2+L9(Cl)]+, and [Fe2+L10(Cl)]+) were compared to identify the effect of structural and electronic properties on catalytic efficiency. Specifically, catalyst complexes were compared to evaluate the effect of five properties on catalyst reaction yields: (1) the coordination requirements of the catalyst, (2) redox half-potential of each complex, (3) topological constraint/rigidity, (4) N atom modification(s) increasing oxidative stability of the complex, and (5) geometric parameters. The need for two labile cis-coordination sites was confirmed based on a 42% decrease in catalytic reaction yield observed when complexes containing pentadentate ligands were used in place of complexes with tetradentate ligands. A strong correlation between iron(III/II) redox potential and catalytic reaction yields was also observed, with [Fe2+L6(Cl)2] providing the highest yield (81%, -405 mV). A Lorentzian fitting of redox potential versus yields predicts that these catalysts can undergo more fine-tuning to further increase yields. Interestingly, the remaining properties explored did not show a direct, strong relationship to catalytic reaction yields. Altogether, these results show that modifications to the ligand scaffold using fundamental concepts of inorganic coordination chemistry can be used to control the catalytic activity of macrocyclic iron complexes by controlling redox chemistry of the iron center. Furthermore, the data provide direction for the design of improved catalysts for this reaction and strategies to understand the impact of a ligand scaffold on catalytic activity of other reactions.
C-vinylation of 1-vinylpyrroles with benzoylacetylene on silica gel
Trofimov,Stepanova,Sobenina,Mikhaleva,Ushakov,Elokhina
, p. 1878 - 1882 (2001)
1-Vinylpyrroles readily add to benzoylacetylene on grinding the reagents with silica gel at room temperature to form 2-(E)-(2-benzoylvinyl)-1-vinylpyrroles in 50-84% yield in a regioand stereoselective manner.
A highly efficient and stereoselective cycloaddition of nitrones to N-vinylpyrroles
Molchanov, Alexander P.,Savinkov, Ruslan S.,Stepakov, Alexander V.,Starova, Galina L.,Kostikov, Rafael R.,Barnakova, Victoriya S.,Ivanov, Andrey V.
, p. 771 - 780 (2014)
1,3-Dipolar cycloadditions of a number of C-aryl, C-carbamoyl-, and C,C-bis(methoxycarbonyl)nitrones and substituted N-vinylpyrroles proceed with high efficiency and regioselectivity with the formation of only one isomeric substituted 5-(1H-pyrrol-1-yl)isoxazolidine cycloadduct. Georg Thieme Verlag Stuttgart · New York.
Mechanistic Insights into Iron-Catalyzed C-H Bond Activation and C-C Coupling
Brewer, Samantha M.,Schwartz, Timothy M.,Mekhail, Magy A.,Turan, Lara S.,Prior, Timothy J.,Hubin, Timothy J.,Janesko, Benjamin G.,Green, Kayla N.
, p. 2467 - 2477 (2021)
Iron-catalyzed C-C coupling reactions of pyrrole provide a unique alternative to the traditional Pd-catalyzed counterpart. However, many details regarding the actual mechanism remain unknown. A series of macrocyclic iron(III) complexes were used to evaluate specifics related to the role of O2, radicals, and μ-oxodiiron-complex participation in the catalytic cycle. It was determined that the mononuclear tetra-Azamacrocyclic complex is a true catalyst and not a stoichiometric reagent, while more than one equivalent of a sacrificial oxidant is needed. Furthermore, the reaction does not proceed through an organic radical pathway. μ-Oxodiiron complexes are not involved in the main catalytic pathway, and the dimers are, in fact, off-cycle species that decrease catalytic efficiency.
Intramolecular H-atom abstraction in γ-azido-butyrophenones: Formation of 1,5 ketyl iminyl radicals
Muthukrishnan, Sivaramakrishnan,Sankaranarayanan, Jagadis,Klima, Rodney F.,Pace, Tamara C. S.,Bohne, Cornelia,Gudmundsdottir, Anna D.
, p. 2345 - 2348 (2009)
Photolysis of γ-azidobutyrophenone derivatives yields 1,4 ketyl biradicals via intramolecular H-atom abstraction. The 1,4 ketyl biradicals expel a nitrogen molecule to form 1,5 ketyl iminyl biradicals, which decay by ring closure to form a new carbon-nitr
PYRROLES FROM KETOXIMES AND ACETYLENE. 39. EFFECT OF THE NATURE OF THE ALKALI METAL CATION AND THE SOLVENT ON THE REACTION RATE IN MOH-DMSO SYSTEMS
Korostova, S. E.,Shevchenko, S. G.,Polubentsev, E. A.,Mikhaleva, A. I.,Trofimov, B. A.
, p. 635 - 638 (1989)
The principal tendencies of the effect of the nature of the cation of the hydroxide (Li+, Na+, K+, Rb+, Cs+), and the solvent (DMSO, hexamethylphosphoric triamide (HMPT), 1-methyl-2-pyrrolidone, sulfolane, DMF, polyethylene glycol, hydrazine hydrate, tetramethylurea), and the additive (cesium and rubidium salts and linear macrocyclic polyethers) in the KOH-DMSO catalytic system on the processes involved in the pyrrolization of acetophenone oxime with acetylene and the vinylation of the resulting 2-phenylpyrrole were ascertained.
2-phenylpyrrole: One-pot selective synthesis from acetophenone oxime and acetylene by a Trofimov reaction
Mikhaleva,Petrova,Sobenina
, p. 1367 - 1371 (2012)
We have developed a technologically orientated, one-pot way of synthesis of high purity 2-phenylpyrrole in 74% yield by treatment of acetophenone oxime with acetylene in the KOH-DMSO system. The reaction is carried out at 135-150°C under an acetylene atmospheric pressure. The synthesis was performed in laboratory (glass apparatus) and in a large scale (10 l reaction vessel).
Regioselective C3-Phosphonation of Free Indoles via Transition-Metal-Free Radical/Hydrolysis Cascade
Guo, Shengmei,Jie, Kun,Zhang, Zhebin,Fu, Zhengjiang,Cai, Hu
, p. 1808 - 1814 (2019)
The selectivity is of great importance for the preparation of molecules in organic chemistry. Herein, a novel method to enable the highly regioselective C3-phosphonation of free indoles has been developed. This transformation involves a radical and a hydrolysis procedure, and tolerates a range of functional groups, which gives an efficient route toward the 1H-indol-3 – ylphosphonic acid monoesters in one step.
Asymmetric Alkylation of Ketones Catalyzed by Engineered TrpB
Arnold, Frances H.,Buller, Andrew R.,Dunham, Noah P.,Straathof, Sabine,Turi, Soma,Watkins-Dulaney, Ella J.
supporting information, p. 21412 - 21417 (2021/08/20)
The β-subunit of tryptophan synthase (TrpB) catalyzes a PLP-mediated β-substitution reaction between indole and serine to form L-Trp. A succession of TrpB protein engineering campaigns to expand the enzyme's nucleophile substrate range has enabled the biocatalytic production of diverse non-canonical amino acids (ncAAs). Here, we show that ketone-derived enolates can serve as nucleophiles in the TrpB reaction to achieve the asymmetric alkylation of ketones, an outstanding challenge in synthetic chemistry. We engineered TrpB by directed evolution to catalyze the asymmetric alkylation of propiophenone and 2-fluoroacetophenone with a high degree of selectivity. In reactions with propiophenone, preference for the opposite product diastereomer emerges over the course of evolution, demonstrating that full control over the stereochemistry at the new chiral center can be achieved. The addition of this new reaction to the TrpB platform is a crucial first step toward the development of efficient methods to synthesize non-canonical prolines and other chirally dense nitrogen heterocycles.
