Nanocellulose as a Reaction Media and Stoichiometric Reagent for FeCl₃-Mediated Reductive Functionalization of Nitro Compounds

Abstract

Among a wide array of synthetic amides, N-aryl/alkyl amides are an important class of structural motifs having significant importance in pharmaceutical and agrochemical industries. In this regard, a rapid, low-cost, and environmentally friendly synthesis of Naryl/alkyl amides still remains in a high demand. Herein, we report a convenient route for the mechanochemical synthesis of N-aryl/alkyl amides via FeCl 3 -catalyzed reductive amidation of nitro compounds, as well as acylation of aliphatic/aromatic amines with carboxylic acids using nanocellulose as the reaction media/stoichiometric reducing agent. The protocol was found to be simple, efficient, and environmentally benign to obtain a diverse array of the respective amides with good to excellent yields. Furthermore, the use of nitro compounds, amines, and carboxylic acids as cheap and readily available starting materials, FeCl 3 as a nontoxic catalyst, and nanocellulose as the biodegradable reaction media as well as the stoichiometric reducing agent makes this protocol in the category of a green chemical transformation.

Mechanochemical Synthesis of Trifluoromethyl Arenes: Nanocellulose-Supported Deaminative Trifluoromethylation of Aromatic Amines

“…In the current paper, we present a new methodology that enables the efficient installation of the CF 3 functionality onto aromatic substrates through ipso -substitution of the NH 2 group using a commercially available pyrylium tetrafluoroborate reagent (Pyry-BF 4 ) and utilization of nanocellulose as the reaction medium. Furthermore, in our recent studies we noticed that nanocellulose can act as the best reaction medium for various mechanochemical transformations including reductive amidation of nitro compounds and for the synthesis of 3-acylchromones via dehydrative cross-coupling between ortho -hydroxyarylenaminones and carboxylic acids …”

“…In recent years, nanocellulose has received significant attention in mechanochemical transformations due to its unique physical and chemical properties. , Apart from having substantial biodegradability, nanocellulose possesses a high specific surface area, high crystallinity, high mechanical strength, and controllable reactive surface . The specific morphology including large surface area makes nanocellulose so effective as a solid reaction medium under the ball milling conditions. ,, Due the fully controllable reactivity, nanocellulose has also shown potential to be used as an additive, catalyst, or catalyst support in many organic transformations. , …”

“…In continuation of our longstanding interest to design sustainable transformations to access organofluorine compounds, ,,,− herein we report a convenient one-pot procedure for the mechanochemical synthesis of trifluoromethyl arenes through the selective transformation of aromatic amino group into the trifluoromethyl functionality using pyrylium tetrafluoroborate (Pyry-BF 4 ) and TMSCF 3 via in situ formation of the pyridinium salt intermediate. The scope of the present protocol includes synthesis of 28 trifluoromethyl arene derivatives in excellent yields via a selective substitution (S N Ar) of an aromatic amino group with CF 3 functionality.…”