Hydroaminomethylation in Aqueous Solvent Systems – An Efficient Pathway to Highly Functionalized Amines

Abstract

Tandem‐catalyzed hydroaminomethylation is a useful tool for synthesizing linear amines from olefins and amines in an atom‐efficient manner. To enable the coupling of highly functionalized, hydrosoluble amines with non‐water‐soluble olefins, this reaction must be transferred to aqueous biphasic solvent systems. In this work, we systematically evaluate reaction conditions to provide a selective hydroaminomethylation of 1‐octene with diethanolamine as model substrates. Although water is both the condensation side product and the solvent, yields of 79% were achieved using a catalytic system consisting a rhodium precursor and a sulfonated diphosphine ligand. This approach was applied to other functionalized amines, proving this concept is a suitable tool for the catalytic alkylation of highly functionalized amines.magnified image

Reusable Catalysts for Hydroformylation‐Based Reactions

“…Vorholt et al [161,162] reported a sustainable strategy for hydroaminomethylation, under aqueous biphasic conditions, using Rh/sulfoxantphos as catalyst, oct-1-ene as substrate and diethanolamine as nucleophile, at 100°C temperature and P(CO/H 2 1 : 3) = 50 bar, finding up to 85 % of olefin conversion after 6 h and 79 % selectivity for the desired amine (Table 3, entry 1).…”

“…However, reutilization studies for this catalyst were not reported. 1 Vorholt [162] Oct-1-ene (T = 100°C, P = 50 bar (CO/H 2, 1 : 3), 6 h)…”

Recycling of two molecular catalysts in the hydroformylation/aldol condensation tandem reaction using one multiphase system

“…Xantphos and its sulfonated, water-soluble variation sulfoXantphos are well known hydroformylation ligands that give high linear to branched ratios due to their wide bite angle (111°) and were successfully applied for hydroformylation reactions in the past. [32][33][34] We then focussed on finding a suitable catalyst for the aldol condensation step. Inorganic bases, such as sodium or potassium hydroxide are the most common catalysts in aldol reactions.…”

“…30,31 Furthermore, aqueous multiphase catalysis has been successfully used for catalyst recycling in the hydroaminomethylation tandem reaction. 32 While hydroformylation and aldol condensation alone have often been studied in liquid/liquid systems, to our knowledge, the tandem reaction has not been demonstrated in such a manner. In this work, we therefore set out to apply multiphase catalysis to perform the hydroformylation/aldol condensation tandem reaction with special focus on recycling of both catalysts simultaneously.…”

Aqueous Biphasic Hydroaminomethylation Enabled by Methylated Cyclodextrins: Sensitivity Analysis for Transfer into a Continuous Process

“…Another example of this was the hydroaminomethylation of isoprene . The approach for the hydroaminomethylation of higher alkenes in aqueous solvent systems was yet only realized for a few selected examples on a small scale using additional surfactants, − such as quaternary ammonium compounds, a cosolvent such as 1-butanol, macroligands to form a micellar system, rhodium nanoparticles, , or mass transfer agents (MTAs) such as cyclodextrins (CDs) . These examples are compared in more detail together with the results of this work in Table .…”