C−H Mono‐Nitration of Indolines using tert‐Butyl Nitrite

Abstract

Nitration reactions on non-prefunctionalized aromatic or heteroaromatic compounds are generally done under harsh conditions. However, these reactions are nonselective to mono-substitution and often produce a mixture of products. Herein we report a mild mono-nitration reaction on indolines, either at À C 5 or À C 7 positions, with 100% regioselectivity using tert-butyl nitrite. The reactions are carried out in acetonitrile and without any additives except nitrating agent tert-butyl nitrite.

Synthetic Protocols for Aromatic Nitration: A Review

“…However, Authors found that acetonitrile is the best solvent in terms of yield. In addition, nitration of a wide range of heterocyclic compounds can be done effectively, making this approach a wide range of synthetic and commercial utility [17] …”

“…In addition, nitration of a wide range of heterocyclic compounds can be done effectively, making this approach a wide range of synthetic and commercial utility. [17] A copper-catalyzed C-5 Nitration of indolines disclosed by Gao et al using tert-butyl nitrate as a nitrating agent (Scheme 10). On the basis of plausible mechanism given by authors shows that NO 2 and tert butoxy radical generated from tert-butyl nitrite.…”

“…[57] Ali Maleki and Morteza Aghaie developed ultrasonicassisted aromatic nitration by using SO 3 H-immobilized silicacoated Fe 3 O 4 nanoparticles used as heterogeneous strong acidic catalysts and sodium nitrate as a nitrating agent in deep eutectic solvent (DES) at room temperature (Scheme 49). Deep eutectic solvents are systems made from a eutectic mixture of Bronsted or Lewis acids and bases and that contain variety of anionic and/or cationic species [17]. Authors found that low frequency of 40 kHz and the power of 250 W in sonication instrument is best preferable condition.…”

Visible-Light-Induced Recyclable g-C3N4 Catalyzed C–H Hydroxylation of Quinoxalin-2(1H)-ones

“…Very recently, P. Mal and co-workers reported a TBN ( tert -butyl nitrite) promoted one-pot hydroxylation of quinoxalin-2(1 H )-ones via nitration at the C3-poisition, followed by ipso -substitution with water (Scheme 1b ). 14 However, this novel method has the disadvantage of requiring high temperature (100 °C) and the use of toxic nitrating reagent. Therefore, from an eco-friendly point of view, a more sustainable and greener solution to direct C–H hydroxylation of quinoxalin-2(1 H )-ones is still an urgent demand.…”

B(C6F5)3-Catalyzed Highly Chemoselective Reduction of Isatins: Synthesis of Indolin-3-ones and Indolines

“…In the case of 1-tosylisatins bearing a methoxy group at the C5 or C6 position, the targeted products 4h and 4i were prepared in moderate yields of 32% and 56%, respectively, while in contrast to other substrates, the yields of indoles 3h and 3i were higher (66% and 22%, respectively) for these substrates. The reaction with N -butylsulfonyl- and N -benzyl-protected isatins 1l and 1m led to give the corresponding products 4l and 4m , in yields of 89% and 53%, respectively.…”