Catalytic direct hydrocarboxylation of styrenes with CO2 and H2

Abstract

A three-component hydrocarboxylation of an olefin with CO2 and H2 could be regarded as a dream reaction, since it would provide a straightforward approach for the synthesis of aliphatic carboxylic acids in perfect atom economy. However, this transformation has not been realized in a direct manner under mild conditions, because boosting the carboxylation with thermodynamically stable CO2 while suppressing the rapid hydrogenation of olefin remains a challenging task. Here, we report a rhodium-catalysed reductive hydrocarboxylation of styrene derivatives with CO2 and H2 under mild conditions, in which H2 served as the terminal reductant. In this approach, the carboxylation process was largely accelerated by visible light irradiation, which was proved both experimentally and by computational studies. Hydrocarboxylation of various kinds of styrene derivatives was achieved in good yields without additional base under ambient pressure of CO2/H2 at room temperature. Mechanistic investigations revealed that use of a cationic rhodium complex was critical to achieve high hydrocarboxylation selectivity.

Visible Light‐Driven, Persulfate‐Mediated Hydrocarboxylation of Vinylsulfones

“…As such, this methodology enables the use of simple, non‐functionalized reagents regardless to its redox potential; and it was successfully applied for various hydrofunctionalization processes by means of C−H activation [9] . As for (hydro)carboxylation purposes; various methods via reductive activation of gaseous CO 2 by SET have been recently exploited [10–15] . Furthermore, a few strategies for the activation of formate salts via HAT have been also reported.…”

“…[9] As for (hydro)carboxylation purposes; various methods via reductive activation of gaseous CO 2 by SET have been recently exploited. [10][11][12][13][14][15] Furthermore, a few strategies for the activation of formate salts via HAT have been also reported. As such, the CÀ H bond of a formate (BDE = 86 kcal/mol) [16] is activated by means of photoinduced HAT, affording carbon dioxide radical anion (CO 2 *À ).…”

Recent Advances in Catalyst Design for Carboxylation Using CO2 as the C1 Feedstock

“…and highly polarized C-metal bonds to less polarized C-(pseudo) halide bonds, unsaturated hydrocarbons, and C-H bonds (Scheme 2) [37]. However, some stochiometric metallic reductants (Mn, Zn) are poisonous, and their reaction requires a harsh environment, which causes pollution by emitting CO 2 [38]. To overcome these issues, it is essential to discover a new route that is environmentally benign to produce carboxylic acid and its derivatives.…”

Synthesis and Reactivity of Ruthenium(BINAP)(PPh3)

“…For example, biaryl-based phosphines (Buchwald ligands) stabilizing Pd-(0) [3] have revolutionized the field of Pd cross-coupling reactions and led to numerous industrial applications. [4][5][6][7] Similar stabilizing strategies have been applied to various phosphine-based complexes of other metals in low oxidation states, including Ni(0), [8] Cu(I), [9] Rh(I), [10][11] Ir(I), [12][13] Pt-(0), [14] Au(I), [15][16] but not Ru(0).…”