Glycerol Boosted Rh‐Catalyzed Hydroaminomethylation Reaction: A Mechanistic Insight

Abstract

We report aR h-catalyzedh ydroaminomethylation reaction of terminal alkenes in glycerolt hat proceeds efficiently under mild conditions to produce the corresponding amines in relatively high selectivity towards linear amines, moderate to excellent yields by using al ow catalyst loading (1 mol %[ Rh],2mol %p hosphine) and relative low pressure (H 2 /CO, 1:1, total pressure 10 bar). This work sheds light on the importance of glycerol in enabling enamine reduction via hydrogen transfer.M oreover,e vidence for the crucial role of Rh as chemoselective catalyst in the condensation step has been obtained for the first time in the frame of the hydroaminomethylation reaction by precluding deleterious aldol condensation reactions. The hydroaminomethylation proceeds under am olecular regime;t he outcomeo f catalytically actives peciesi nto metal-based nanoparticles renderst he catalytic system inactive.

Coordination assembly enables highly selective catalytic hydroaminomethylation of olefins

“…8,11,12 Therefore, various efforts have thus been devoted to the design of bi-functional catalytic systems. [20][21][22][23][24][25][26][27] By using 2-fluoro-4-methylbenzoic acid as a co-catalyst, Abolhasani and co-workers increased the reactivity of Rh/4,5-bis(diphenylphosphino)-9,9-dimethyl-xanthene by 70-fold in HAM. 20 Chen's group synthesized water-soluble diphosphine ligands and applied them in Rh-catalyzed HAM of vinylarenes using anilines in water with good branch selectivity.…”

“…21 Despite these advances, various stoichiometric additives still have to be added to achieve satisfactory yields and regioselectivity. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] In contrast, heterogeneous catalytic systems that are effective for HAM are still few in number, and those with industrial potential are even rarer. Poor selectivity (usually <80 : 20 for l/b) with limited substrate scope, limited reusability and decreasing activity in <5 reactions was generally observed with supported Rh and Ru nanoparticles (Fig.…”

Recyclable cooperative catalyst for accelerated hydroaminomethylation of hindered amines in a continuous segmented flow reactor

“…This is a significant drawback that has limited the scope of HAM reactions to non-hindered amines 13 , 14 . Recent studies have demonstrated advances in the rate acceleration and substrate scope expansion of HAM reactions 15 , 16 . However, examples of HAM with sterically hindered amines are rare, and alternative complex routes are developed specifically for their alkylation 17 .…”

Hydroaminomethylation of Natural Allylic and Homoallylic Alcohols: A Ligand‐Controlled Route to New Amines

“…Due to the further development of more efficient cobalt and rhodium catalysts and the introduction of phosphorus ligands, HAM has become a powerful method for the synthesis of amines. [4][5][6][7][8][9][10][11][12][13][14][15] As HAM is a tandem catalytic process in which various catalytic cycles occur simultaneously, the conditions can be good for one catalytic cycle and deleterious for the other. For this reason, care in the choice of appropriate conditions is critical for the successful reaction sequence.…”

“…However, selectivity for amines was low and the reaction required harsh conditions (T>300 °C and pressures up to 150 bar). Due to the further development of more efficient cobalt and rhodium catalysts and the introduction of phosphorus ligands, HAM has become a powerful method for the synthesis of amines [4–15] . As HAM is a tandem catalytic process in which various catalytic cycles occur simultaneously, the conditions can be good for one catalytic cycle and deleterious for the other.…”