The Last Fortress of Tin's Tyranny – Protodenitration of Nitroalkanes

Abstract

Protodenitration, a direct reduction of nitroalkanes to corresponding alkanes, already spans two centuries and is enabled by various reagents. This mini-review provides a historical development of the fundamental transformation and highlights the governing position of the Ono-Tanner reaction employing tributyltin hydride. Due to the unchallenged dominance of the toxic tributyltin hydride and environmentally unpopular solvents sharply contrasting with modern ecological trends, the current situation was dubbed "the last fortress of tin's tyranny."[a

More Chips to Nitroolefins: Decatungstate Photocatalysed Hydroalkylation Under Batch and Flow Conditions

“…[5] Moreover, the nitro group can be smoothly converted under mild conditions into a plethora of different functional groups, including amines, oximes, aldehydes, ketones and carboxylic acids, [6] or even removed via a denitration reaction. [7] More recently, the behaviour of nitroalkenes under irradiation conditions has been also investigated, and their reactivity applied to [2 + 2] cycloadditions, [8] as well as a tool to perform both stereo- [9] and regioisomerizations. [10] On the other hand, the reactivity of nitro compounds under conditions involving open-shell species, has been explored only to a limited extent.…”

Synthetic Approaches to the Challenging Direct C‐Alkylation and C‐Allylation of Unactivated Nitroalkanes

“…[1][2][3] The close similarity of this behavior with the flourishing chemistry of enolate systems is supported by the existence of a keto-enol type equilibrium involving the nitroalkane and its nitronic acid tautomer (aci/nitro equilibrium) (Scheme 1). Thus, considering the low pKa values evidenced for simple nitroalkanes (7)(8)(9)(10), conversion of the nitronic acid into the corresponding nitronate anion can be readily pursued using basic reagents of moderate strength. This aspect has favored the success of nitroalkanes as easy to handle carbanionic reagents amenable of generating new CÀ C bonds in the reaction with carbon centered electrophiles.…”

“…The interest in nitro-embedding structural entities is further boosted by the manyfold synthetic manipulation of the nitro group which can be reduced to a primary amine, [4,5] converted into a carbonyl system, [6][7][8] or definitively removed by reductive methods (denitrations) or exploiting base-induced elimination processes. [9][10][11] The nitronate anion 1, once generated from the corresponding nitroalkanes, can be involved in several reactions with different electrophilic species as portrayed in Scheme 2. The nucleophilic addition of 1 to aldehydes known as the nitroaldol (Henry) reaction is a very effective process which can be catalyzed by a plethora of basic catalysts/promoters leading to nitro alcohols 2.…”

“…This aspect has favored the success of nitroalkanes as easy to handle carbanionic reagents amenable of generating new C−C bonds in the reaction with carbon centered electrophiles. The interest in nitro‐embedding structural entities is further boosted by the manyfold synthetic manipulation of the nitro group which can be reduced to a primary amine, [4,5] converted into a carbonyl system, [6–8] or definitively removed by reductive methods (denitrations) or exploiting base‐induced elimination processes [9–11] . The nitronate anion 1 , once generated from the corresponding nitroalkanes, can be involved in several reactions with different electrophilic species as portrayed in Scheme 2.…”