A Ag2CO3/TFA-catalyzed intramolecular annulation approach to imidazo[1,2-c][1,3]oxazin-5-one derivatives

Abarbri, Mohamed; Qami, Abdelkarim El; Jismy, Badr; Akssira, Mohamed; Jacquemin, Johan; Tikad, Abdellatif

doi:10.1039/d1ob02352g

Cited by 3 publications

References 76 publications

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Regioselective C6‐Arylation of Thieno[3,2‐c]pyrazole Heterocycles with Aryl Iodides

Ait Lfakir,

Jismy,

Guillaumet

et al. 2024

Adv Synth Catal

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Efficient and regioselective C6‐arylation of thieno[3,2‐c]pyrazoles with aryl iodides as coupling partners has been developed. This strategy was performed in the presence of Pd(OAc)2 as catalyst in combination with AgOTf as an oxidant and TFA in dimethylacetamide. In all experiments, only the C6‐arylated thieno[3,2‐c]pyrazole was isolated since its C5‐regioisomer was not observed, indicating the high regioselectivity of this approach. The catalytic system used is compatible with a variety of 3‐functionalized thieno[3,2‐c]pyrazoles and iodoaryl electrophiles, providing access to novel 3,6‐disubstituted thieno[3,2‐c]pyrazoles in moderate to good yields.

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Regioselective C6‐Arylation of Thieno[3,2‐c]pyrazole Heterocycles with Aryl Iodides

Ait Lfakir,

Jismy,

Guillaumet

et al. 2024

Adv Synth Catal

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Five-membered ring systems: with more than one N atom

Yet

2023

Progress in Heterocyclic Chemistry

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Efficient Synthesis of 1H-Benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one Derivatives Using Ag2CO3/TFA-Catalyzed 6-endo-dig Cyclization: Reaction Scope and Mechanistic Study

Qami

Jismy

Akssira³

et al. 2023

Molecules

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A small library of 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one derivatives was prepared in good to excellent yields, involving a Ag2CO3/TFA-catalyzed intramolecular oxacyclization of N-Boc-2-alkynylbenzimidazole substrates. In all experiments, the 6-endo-dig cyclization was exclusively achieved since the possible 5-exo-dig heterocycle was not observed, indicating the high regioselectivity of this process. The scope and limitations of the silver catalyzed 6-endo-dig cyclization of N-Boc-2-alkynylbenzimidazoles as substrates, bearing various substituents, were investigated. While ZnCl2 has shown limits for alkynes with an aromatic substituent, Ag2CO3/TFA demonstrated its effectiveness and compatibility regardless of the nature of the starting alkyne (aliphatic, aromatic or heteroaromatic), providing a practical regioselective access to structurally diverse 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones in good yields. Moreover, the rationalization of oxacyclization selectivity in favor of 6-endo-dig over 5-exo-dig was explained by a complementary computational study.

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A Ag₂CO₃/TFA-catalyzed intramolecular annulation approach to imidazo[1,2-c][1,3]oxazin-5-one derivatives

Abstract: A series of 2,7-disubstituted 3-methylimidazo[1,2-c][1,3]oxazin-5-one were synthesized in good yields via Ag2CO3/TFA-mediated an intramolecular annulation of N-Boc-2-alkynyl-4-bromo(alkynyl)-5-methylimidazoles. This methodology was carried out in the presence of a catalytic amount of...

Cited by 3 publications

References 76 publications

Regioselective C6‐Arylation of Thieno[3,2‐c]pyrazole Heterocycles with Aryl Iodides

Regioselective C6‐Arylation of Thieno[3,2‐c]pyrazole Heterocycles with Aryl Iodides

Five-membered ring systems: with more than one N atom

Efficient Synthesis of 1H-Benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one Derivatives Using Ag2CO3/TFA-Catalyzed 6-endo-dig Cyclization: Reaction Scope and Mechanistic Study

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