N-formylation of amines using methanol as a potential formyl carrier by a reusable chromium catalyst

Abstract

Formamides represent an abundant class of compounds in organic synthesis. They can be made efficiently by the direct catalytic coupling of methanol with amines in the presence of metal-based catalysts. However, these catalysts require complicated organic ligands, susceptible to oxidative self-degradation, restricting their practical applications. Here, we describe an inorganic ligand-supported chromium (III) catalyst, (NH 4) 3 [CrMo 6 O 18 (OH) 6 ], which consists of a central chromium (III) single-atomic core supported by a cycle-shaped inorganic ligand consisting of six Mo VI O 6 octahedra, shows excellent activity and selectivity. Various primary amines and secondary amines are successfully transformed into the corresponding formamides under mild conditions, and the formylation of primary diamines is also achieved. The chromium catalyst can be reused several times with little loss of the activity. Mechanistic insight is provided based on the observation of an intermediate and control experiments.

Copper‐Catalyzed Formylation of Amines by using Methanol as the C1 Source

“…This family of chemicals can be synthesized by several methods. Most of the traditional methods use excess amounts of formylating agents, such as formic acid, formate, chloral, CO 2 , acetic formic anhydride, carbodiimide, and formaldehyde, which often result in the production of huge amounts of toxic wastes and poor atom economy . These methods also suffer from other drawbacks, such as low yields and the use of expensive, instable, air‐ and moisture‐sensitive, and toxic reagents .…”

“…The pioneering work of Glorius and co‐workers in 2013 was the first example of formylation of amines by methanol activation . However, the number of reports on the application of methanol as a carbonyl precursor using molecular complexes or heterogeneous catalysts remains very low (Scheme ). Therefore, finding mild and feasible reaction conditions for activation and aerobic oxidation of methanol could be the key for the problem of N ‐formylation of amines and remains a challenge.…”

Oxidative N-Formylation of Secondary Amines Catalyzed by Reusable Bimetallic AuPd–Fe3O4 Nanoparticles

“…Among formyl sources, methanol is an ideal C 1 source because of its availability and ecofriendly properties compared with other reagents [ 18 , 19 ]. It is one of the most popular C 1 sources in organic reactions, such as methylation [ 20 , 21 , 22 , 23 , 24 ], formylation [ 25 , 26 , 27 ], and methoxylation [ 28 , 29 , 30 ], forming C–C, C–N, and C–O bonds, respectively. Therefore, developing a new catalytic route for the synthesis of formamides with methanol as a sustainable building block would be a valuable addition to the synthetic toolbox.…”

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.…”