One‐Pot Selective Catalytic Synthesis of Pyrrolidone Derivatives from Ethyl Levulinate and Nitro Compounds

Abstract

N-substituted 5-methyl-2-pyrrolidones were prepared in a one-pot process starting from ethyl levulinate and nitro compounds in the presence of a nanosized Pt-based catalyst. Pt supported on TiO nanotubes (Pt/TiO -NT) catalyzed the synthesis of N-substituted 5-methyl-2-pyrrolidones through a cascade process involving the reduction of nitro compounds, formation of the intermediary imine, hydrogenation, and subsequent cyclization. A bifunctional metal-acid system was a suitable catalyst for the process. Pt supported on TiO showed lower catalytic activity than Pt/TiO -NT owing to the strong adsorption of nitro compounds during the first reaction step that poisoned the acidic sites and strongly decreased the rate of amination and cyclization. However, Pt/TiO -NT with milder acid sites was less affected by the adsorption of nitro compounds and the full cascade process could proceed. The results indicate that the prepared Pt/TiO -NT is a chemoselective and reusable catalyst that can be applied to the synthesis of a variety of N-substituted 5-methyl-2-pyrrolidones starting from nitro compounds with excellent yields in absence of an additional organic solvent under mild reaction conditions.

A Multiphase Protocol for Selective Hydrogenation and Reductive Amination of Levulinic Acid with Integrated Catalyst Recovery

“…[31] Moreover,a t1 20 8C( solvent-free conditions),aquantitative yield of the imine derived from ethyl levulinate anda niline was obtainedi nt he presence of Pt/TiO 2 catalyst, but it was demonstratedt hat the reaction did not require noble-metal catalysis;the process was strongly promoted by the Lewis acidity associated with Ti 4 + sites on the TiO 2 support. [40,41] Additionally,a mides of LA could also be obtainedi n the absence of catalysts ands olvents. [33] Specifically, N-cyclohexyl-4-oxopentanamide, compound B of Scheme 6, was observed in the uncatalyzed reaction of LA and CyNH 2 at 120 8C for 12 h. [38] To speculate on thesea spects, additional experimentsw ere performed in aqueous solution.A ccordingt ot he conditions of entry 10 in Ta ble 2, am ixture of LA (3.6 mmol) and CyNH 2 in a1 :2 molar ratio in water (0.5 mL) was set to react at different temperatures, from ambient up to 100 8C.…”

The Catalytic Reduction of Carboxylic Acid Derivatives and CO2 by Metal Nanoparticles on Lewis‐Acidic Supports

“…Considering that some nitriles and nitro compounds are the intermediates of primary amines, one‐pot reactions of these with LA and H 2 may provide a sustainable and practical route to γ‐lactams ,,. Corma and Iborra have reported the first general method for a one‐pot synthesis of N ‐substituted γ‐lactams via the reductive amination of ethyl levulinate with nitro compounds under 10 bar H 2 using a heterogeneous Pt catalyst, albeit that this method requires large amounts of ethyl levulinate (3 equivalents with respect to the nitro compounds) . As for the use of nitriles as an alternative to primary amines, a patent by Manzer reports the synthesis of N ‐substituted γ‐lactams from LA and 3‐penteneitrile or benzonitrile under H 2 using Pd‐, Rh‐, Ru‐, or Pt‐based catalysts loaded on carbon or Al 2 O 3 .…”

Iron‐Catalyzed Reductive Amination from Levulinic and Formic Acid Aqueous Solutions: An Approach for the Selective Production of Pyrrolidones in Biorefinery Facilities

“…Pyrrolidones can be synthetized by several methods, being reductive amination of keto esters with concomitant lactamization, one of the best way to prepare them. Despite the many examples presented in the literature for conversion of LA into PYR, some of them very efficient, the great majority uses organic solvents as reaction medium, precious metals as catalysts and do not contemplate efforts to scaling‐up processes.…”