Recent Trends in Upgrading of CO₂ as a C1 Reactant in N‐ and C‐Methylation Reactions

Abstract

Carbon dioxide (CO 2 ) capture and conversion from renewable resources have recently emerged as a viable alternative to the synthesis of core chemicals. Despite the fact that CO 2 fixation is limited due to its thermodynamic stability and kinetic inertness, researchers are becoming increasingly interested in developing novel routes with the use of CO 2 in synthetic organic chemistry, and the pace of advancements in this field is accelerating. In particular, the development of benign N-and C-methylation reactions employing CO 2 as a C1 synthon instead of conventional methylation reagents would enable the release of lower amounts of waste leading to more sustainable chemical industry. This review presents recent new strategies for the chemical transformation of CO 2 and its incorporation into Nor C-based nucleophiles to provide access to the respective methylamines and methylated (hetero)arenes. Finally, existing limitations in NÀ H, and CÀ H bond activation techniques and future prospects are also discussed. We believe these methodologies will provide a handy reference to the chemists for synthesizing a vast range of methylated molecules in shorter steps by utilizing CO 2 as an advantageous single-carbon source.

Valorization of bio-renewable glycerol by catalytic amination reactions

“…The dehydration reaction of intermediates (2,4,8,38) with ammonia forms imine intermediates (20, 39, 40, 41) 69 which, followed by condensation and cyclization, leads to the formation of pyridine (36). 69 In the same way, intermediate 60 reacts with ammonia to provide an imine intermediate and in the next step this imine intermediate further reacts with intermediate 60 to produce the oxazoline derivative (57). 42 Similarly, intermediate 15 reacts with an aromatic diamine such as 1,2phenylenediamine (56) and generates the imine intermediate (52), which then undergoes dehydration to give other intermediates 53 and 54.…”

Selective N‐Methylation of N‐Methylaniline with CO2 and H2 over Cu/In2O3 Catalyst†

“…N ‐Methylation of amines with CO 2 and H 2 is a potential approach for CO 2 utilization, because N ‐methylated amines can be used as solvents and organic intermediates for dyes, surfactants, pesticides, etc . [ 4‐7 ] Previously, Cantat and Beller independently developed the methylation of amines with hydrosilanes and CO 2 by homogeneous catalysts. [ 8‐9 ] Unfortunately, the methods were not practical due to the use of expensive hydrosilanes as reducing agents.…”

Tuneable reduction of CO2 – organocatalyzed selective formylation and methylation of amines

“…14 The common C1 sources for N -methylation and N -formylation reactions include MeI, 15 CH 2 N 2 , 16 dimethyl carbonate, 17 methanol, 18 formic acid 19 and CO 2 . 20 In particular, the use of CO 2 in combination with reducing agents is an attractive alternative to toxic and hazardous reagents (Scheme 1a). CO 2 is a waste product of fuel combustion currently deemed as a promising surrogate of carbon feedstocks.…”