Efficient Co(ii) heterogeneously catalysed synthesis of α-aminonitriles at room temperature via Strecker-type reactions

MCM-41 mesoporous silica: a highly efficient and recoverable catalyst for rapid synthesis of α-aminonitriles and imines

“…Indeed, to overcome problems encountered with the use of NaCN, KCN (40), Cu(OTf) 2 (41), Yb (OTf) 3 (42), Ga-TUD-1 (43), Ga(OTf) 3 (44), GaCl 3 (45), CeCl 3 (46), Pr(OTf) 3 (47), RuCl 3 (48), La(NO 3 ) 3 .6H 2 O (49), diethylphosphorocyanidated (30), I 2 (50), FeCl 3 (51), NH 2 SO 3 H (52), L-proline (53), p-toluenesulfonic acid (54), nano-sized TiO 2 (55), Sn-montmorillonite (56), o-benzenedisulfonimide (57), sulfuric acid-modified PEG-6000 (PEG-OSO 3 H) (58), xanthan sulfuric acid (59), cellulose sulfuric acid (60), Nafion-SAC-13 and Nafion-H (61), and chitosan (62) in conventional organic solvents have been developed in past two decades. Furthermore, a few heterogeneous mesoporous nano-ordered silica modified by transition metal cations or strong Bronsted acid centers such as Co/SBA-15 (63,64), Zr-MCM-41 (65), B-MCM-41 (66), SBA-15-Ph-Pr-SO 3 H (67) and MCM-41-SO 3 H (68) have been introduced in recent years. However, most of these homogeneous or heterogeneous catalytic systems and modifications require the use of expensive reagents, harsh reaction conditions, lengthy reaction times, the use of toxic organic solvents, low yields as well as tedious work-up leading to the generation of a large amount of toxic waste (32, 34-37, 42, 43, 50, 61).…”

“…However, most of these homogeneous or heterogeneous catalytic systems and modifications require the use of expensive reagents, harsh reaction conditions, lengthy reaction times, the use of toxic organic solvents, low yields as well as tedious work-up leading to the generation of a large amount of toxic waste (32, 34-37, 42, 43, 50, 61). Consequently, the use of cost-effective and recyclable catalysts as well as avoiding toxic or volatile organic solvents can be a major effort to improve clean and green synthesis of α-aminonitriles (62)(63)(64)67).…”

“…The development of porous materials with large specific surface areas (>1000 m 2 .g −1 ) such as silica-based mesoporous has attracted significant attention with regard to their potential applications in the adsorption, chromatography, gas storage, sensor technology and recoverable solid catalysts in organic synthesis (71). In the case of solid-activated silica-based mesoporous catalysts, mesoporous materials were used as solid support in previous studies performed by our or other research groups (63)(64)(65)(66)(67)(68). Hence, different methods including replacement of Si atoms in the matrix by metal ions such as Al (72), B or Fe (66), and Zr (65) or anchoring acidic organic groups such as 3-sulfonic propyl (67,73) and inorganic sulfonic acid (−SO 3 H) (68) have been described.…”

Three‐component solventless Strecker synthesis of α‐aminonitriles catalysed by a renewable sulfonated nanoporous carbon catalyst (CMK‐5‐SO3H)

“…However, the Strecker reaction has drawbacks, in particular due to the volatile and highly toxic nature of HCN. Among various cyanide sources such as HCN, KCN, NaCN, Bu 3 SnCN, K 4 [Fe (CN) 6 ] and trimethylsilyl cyanide (TMSCN), TMSCN is a desirable cyanide reagent, due to its safety, efficiency and availability. It is also noteworthy that TMSCN cannot transfer to electrophiles by itself and needs a catalyst for its activation.…”

Heterogeneously catalysed Strecker-type reactions using supported Co(ii) catalysts: microwave vs. conventional heating

“…[16][17][18][19] Particularly related to Strecker-type reactions, we recently reported the application of a simple and efficient Co(II) complex supported on mesoporous SBA-15 in the synthesis of a range of aaminonitriles from ketimines and ketiminium salts. 20 This catalyst was also previously employed in a series of heterogeneously catalysed processes, including aerobic oxidations, 16 the chemoselective deprotection of acetates, 17 the acetylation of alcohols 18 and C-heteroatom bond-forming reactions. 19 However, in all cases, the Co(II) complex was always stabilised on SBA-15 and no comparable examples of different supports were attempted in order to investigate the potential effect of the support on the activity of the supported material.…”