Recent advances in liquid hydrosilane-mediated catalytic N-formylation of amines with CO₂

Abstract

This review depicts different types of catalyst systems developed for upgrading of amines and carbon dioxide into N-formylated products in the presence of hydrosilane, with attention on reaction mechanism and process optimization.

Organoaluminum Cation Catalyzed Selective Hydrosilylation of Carbonyls, Alkenes, and Alkynes

“…Mp: 275-285 °C. 1 H NMR (400 MHz, CDCl 3 , 298 K) δ (ppm): 7.28 (s, 6H, ArH), 6.90 (t, 3 J HH = 8.0 Hz, 2H, ArH), 6.68-6.66 (d, 3 J HH = 8.0 Hz, 4H, ArH), 5.20 (s, 2H, NH), 3.08-3.01 (m, 4H, CH 2 CH 3 ), 2.84-2.76 (m, 4H, CH 2 CH 3 ), 2.42-2.33 (m, 4H, CH 2 CH 3 ), 2.26-2.17 (m, 4H, CH 2 CH 3 ), 1.36 (t, 3 J HH = 8.0 Hz, 12H, CH 2 CH 3 ), 0.97 (t, 3 J HH = 8.0 Hz, 12H, CH 2 CH 3 ), À 0.94 (s, 6H, Al(CH 3 ) 2 ). 13…”

“…Mp: 255-260 °C. 1 H NMR (700 MHz, CDCl 3 , 298 K) δ (ppm): 7.17-7.13 (m, 6H, ArH), 6.77-6.72 (m, ArH), 6.64 (t, 3 J HH = 8.0 Hz, 3H, ArH), 5.46 (s, 1H, NH), 3.02-2.98 (m, 4H, CH 2 CH 3 ), 2.79-2.74 (m, 2H, CH 2 CH 3 ), 2.72-2.65 (m, 2H, CH 2 CH 3 ), 2.42-2.37 (m, 4H, CH 2 CH 3 ), 2.28 (m, 4H, CH 2 CH 3 ), 1.33 (t, 3 J HH = 8.0 Hz, 6H, CH 2 CH 3 ), 1.14 (t, 3 J HH = 8.0 Hz, 6H, CH 2 CH 3 ), 1.10 (t, 3 J HH = 8.0 Hz, 6H, CH 2 CH 3 ), 0.99 (t, 3 J HH = 8.0 Hz, 6H, CH 2 CH 3 ), À 1.03 (s, 6H), À 1.24 (s, 6H, (Al(CH 3 ) 2 ) 2 ). 13…”

“…[2] Thus, commercially available liquid hydrosilanes are attractive due to their mild and easy handling. [3] Various transition metal-based catalysts have been employed for the hydrosilylation of carbonyls. [4] Despite the stability and efficiency of these catalysts, they raise environmental and safety issues.…”

Catalyst free N-formylation of aromatic and aliphatic amines exploiting reductive formylation of CO2 using NaBH4

“…There is considerable interest in the synthesis of N-formyls directly from feedstock chemicals with high atom and economic efficiency. Methods have been developed where methanol, [15][16][17] CO 18 and CO 2 [19][20][21][22][23][24][25][26][27][28] have been exploited as a formyl surrogate employing various catalysts including transition metals. Carbon dioxide (CO 2 ) is a notorious greenhouse gas but an inexpensive, non-toxic, and abundant source of carbon in synthetic organic chemistry.…”

“…[29][30][31][32] Recently, CO 2 has been used as a formyl surrogate for the synthesis of N-formyls in the presence of a reductant. [19][20][21][22][23][24][25][26][27][28] However, most of these reported methodologies require expensive or complex metal based catalysts [20][21][22]24,[26][27][28] as well as ligands along with hydrogen gas or hydrosilanes 19,25 as a source of hydride under high temperature and pressure. Although these reported methods use substoichiometric amounts of catalysts, still these transformations are far from ideal due to limited product scope as well as poor energy and economic efficiency.…”