Replacement of the Aromatic Primary Amino Group by Hydrogen*National Research Fellow, 1942–1943. Present address, Purdue University.

Abstract

The replacement of an aromatic primary amino group by hydrogen is usually effected by the reduction of the diazonium salt derived from the amine. It is evident that the success of the deamination process is a function of the completeness of diazotization as well as of the reduction. Diazonium compounds have been treated with a great variety of reducing agents some of which have become incorporated into procedures for replacing the diazo group by hydrogen. The important process involve reduction by: alcohols, hypophosphorous acid, alkaline formaldehyde, stabilization of the diazonium salt with naphthalene‐1,5‐disulfonic acid followed by treatment with zinc or copper, sodium stannite, stannous chloride or sodium sulfate reduction to hydrazine from which the hydrocarbon is obtained by oxidation.

Salicylic Acid‐Catalyzed One‐Pot Hydrodeamination of Aromatic Amines by tert‐Butyl Nitrite in Tetrahydrofuran

“…Typically, this transformation is achieved by the initial formation of the corresponding arenediazonium salt, followed by a hydrodediazotization. A plethora of reductive protocols have been implemented with this purpose, involving different hydrogen donors, namely: alcohols, H 3 PO 3 , NO/THF, Et 3 N, catalytic Fe(II) in DMF, and trichlorosilane . Recently, a visible‐light promoted reaction catalyzed by Eosin B in DMF has also been reported .…”

Toward the Design of Molecular Chameleons: Flexible Shielding of an Amide Bond Enhances Macrocycle Cell Permeability

“…The nitro group of 7a – e was removed in a three-step sequence. First, the nitro group was reduced to an amine using hydrogenation; then, the amine was transformed into a diazonium moiety using catalytic amounts of copper­(I) oxide and sodium nitrite followed by reduction using hypophosphorus acid. , During these steps, a side product having a molecular weight 2 Da lower than the desired product was observed for each of the five macrocycles. As the mixtures were difficult to purify, they were oxidized by IBX − at 85 °C, which provided 8a – e in 12–25% yields.…”

Reductive Denitration of Nitroarenes

“…Previously reported reactions are only applicable to specific substrates, such as highly electron-deficient and amino-substituted nitroarenes, and suffer from low yields of the parent arenes and/or the formation of side products . The difficulties associated with the reductive denitration can be attributed to the inherent reactivity of the nitro group: under reducing conditions nitroarenes are usually converted into anilines and/or other reduced species, such as nitroso compounds and hydroxylamines. , As a result, the removal of nitro groups on aromatic rings commonly requires the formation of the corresponding anilines and two additional synthetic manipulations, namely diazotization followed by a Sandmeyer-type reaction (Figure , path A) . Unfortunately, these processes may suffer from a limited substrate scope, as the use of strong acids largely diminishes the functional-group tolerance.…”