Electrochemical Cyclization of o-Aminyl Azobenzenes: Roles of Aldehydes in N–N Bond Cleavage DOI
Anni Li,

Anna Gao,

K. K. N. CHEN

et al.

Organic Letters, Journal Year: 2024, Volume and Issue: 26(30), P. 6324 - 6329

Published: July 22, 2024

Direct functionalization of azobenzenes provides an approach to obtaining valuable molecules in synthetic chemistry. However, efficient method for the cleavage N═N bond azobenzenes, which is a key process this transformation, still lacking. We herein disclose electrochemical reduction-induced cyclization with aldehydes via cleavage. This proceeds well absence any transition metals or external chemical oxidants, leading formation N-protected benzimidazoles moderate good yields.

Language: Английский

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives DOI Creative Commons
Yi Liu, Puying Luo, Yang Fu

et al.

Beilstein Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 17, P. 2462 - 2476

Published: Sept. 22, 2021

Great progress has been made in the tandem annulation of enynes past few years. This review only presents corresponding reactions 1,3-enyne structural motifs to provide functionalized pyridine and pyrrole derivatives. The functionalization cover iodination, bromination, trifluoromethylation, azidation, carbonylation, arylation, alkylation, selenylation, sulfenylation, amidation, esterification, hydroxylation. We also briefly introduce applications products reaction mechanisms for synthesis N-heterocycles.

Language: Английский

Citations

26
Multicomponent syntheses of 5- and 6-membered aromatic heterocycles using group 4–8 transition metal catalysts DOI Creative Commons
Daniel N. Huh, Yukun Cheng, Connor W. Frye

et al.

Chemical Science, Journal Year: 2021, Volume and Issue: 12(28), P. 9574 - 9590

Published: Jan. 1, 2021

In this Perspective, we discuss recent syntheses of 5- and 6-membered aromatic heterocycles via multicomponent reactions (MCRs) catalyzed by group 4–8 transition metals, with a focus on common mechanisms synthetic strategies across the series.

Language: Английский

Citations

24
Evaluation of Tungsten Catalysis among Early Transition Metals for N-Aryl-2,3,4,5-tetraarylpyrrole Synthesis: Modular Access to N-Doped π-Conjugated Material Precursors DOI
Hayato Tsurugi, Takuya Akiyama, Connor W. Frye

et al.

Inorganic Chemistry, Journal Year: 2024, Volume and Issue: 63(6), P. 3037 - 3046

Published: Feb. 1, 2024

Low-valent tungsten species generated from WCl6 and N,N′-bis(trimethylsilyl)-2,5-dimethyldihydropyrazine (Si-Me2-DHP) promotes the catalytic formation of N-phenyl-2,3,4,5-tetraarylpyrroles 3aa-ka diarylacetylenes 1a-k azobenzene (2a). An initial catalyst activation process is a three-electron reduction with Si-Me2-DHP to afford transient 'WCl3' species. Catalytically active bis(imido)tungsten(VI) via successive one-electron N═N bond cleavage 2a was revealed by isolating W(═NPh)2Cl2(PMe2Ph)2 imidotungsten(V) trichloride in presence PMe2Ph. The superior activity clarified density functional theory study: energies for key three steps, [2 + 2]-cycloaddition W═NPh diarylacetylene form (iminoalkylidene)tungsten species, enyne metathesis second diarylacetylene, C–N formation, are reasonable values reaction at 180 °C. In addition, this overcame two distinct deactivation processes: α-enediamido aggregation low-valent both which were observed previously developed vanadium titanium catalysts. We also demonstrated synthetic utility pentaarylpyrroles 3aa 3ba as well N-(2-bromophenyl)-2,3,4,5-tetraarylpyrrole 3ab derivatizing their π-conjugated compounds 9aa, 10ba, 11ab.

Language: Английский

Citations

3
Bonding and Reactivity of d0 Transition Metal Imido Complexes Encoded in Their 15N NMR Signatures DOI
Yuya Kakiuchi, Partha Karmakar,

Jérémy Roudin

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(14), P. 9860 - 9870

Published: March 27, 2024

Terminal imido complexes containing metal–nitrogen multiple bonds have been widely used in organometallic chemistry and homogeneous catalysis. The role of terminal ligands spans from reactive sites to spectator motifs, largely depending on the nature metal center its specific coordination sphere. Aiming at identifying reactivity descriptors for M–N bonds, we herein explore solid-state 15N NMR spectroscopy (ssNMR) early transition augmented by computational studies show that asymmetry parameter, κ (skew, 1 ≥ −1), readily available experiments or calculations, is diagnostic complexes. While inert exhibit skew values (κ) close 1, highly moieties display significantly lower (κ ≪ 1) as found metallocene bis-imido Natural chemical shielding analysis shows away are associated with an asymmetric development π-orbitals around bond moiety, a larger double-bond character imido. Notably, this descriptor does not directly relate M–N–C angle, illustrating shortcoming evaluating bonding hybridization geometrical parameters alone. Overall, enables obtain direct experimental evidence π-loading effect seen bis(imido) related complexes, thus explaining their bonding/reactivity.

Language: Английский

Citations

3
Electrochemical Cyclization of o-Aminyl Azobenzenes: Roles of Aldehydes in N–N Bond Cleavage DOI
Anni Li,

Anna Gao,

K. K. N. CHEN

et al.

Organic Letters, Journal Year: 2024, Volume and Issue: 26(30), P. 6324 - 6329

Published: July 22, 2024

Direct functionalization of azobenzenes provides an approach to obtaining valuable molecules in synthetic chemistry. However, efficient method for the cleavage N═N bond azobenzenes, which is a key process this transformation, still lacking. We herein disclose electrochemical reduction-induced cyclization with aldehydes via cleavage. This proceeds well absence any transition metals or external chemical oxidants, leading formation N-protected benzimidazoles moderate good yields.

Language: Английский

Citations

3