Rhoda‐Electrocatalyzed Bimetallic C−H Oxygenation by Weak O‐Coordination

Abstract

Rhodium-electrocatalyzed arene CÀHo xygenation by weakly O-coordinating amides and ketones have been established by bimetallic electrocatalysis.L ikewise,d iverse dihydrooxazinones were selectively accessed by the judicious choice of current, enabling twofold C À Hf unctionalization. Detailed mechanistic studies by experiment, mass spectroscopy and cyclovoltammetric analysis provided support for an unprecedented electrooxidation-induced CÀHa ctivation by abimetallic rhodium catalysis manifold.

Recent Applications of Homogeneous Catalysis in Electrochemical Organic Synthesis

“…request of the author prior to copyediting and composition. In 2021, the Ackermann group reported electrochemical C-H oxygenation reactions catalyzed by a dimetallic Rh complex.. 67 Instead of a Cp*Rh complex, [Rh(OAc) 2 ] 2 , which has a stable dimeric structure, was used as the catalyst, and the product selectivity could be controlled by varying the quantity of electricity. From amides or ketones 9-1, products 9-3 were obtained with 2.2-2.5 F/mol electricity, whereas reaction of N-Me amides 9-2 at 4.0 F/mol gave annulated products 9-4 (Figure 9a).…”

Electrochemical Hydroxylation of Electron‐Rich Arenes in Continuous Flow

“…1 H NMR of 6 b (400 MHz, CDCl 3 ) δ 7.65 (dd, J = 8.3, 1.9 Hz, 1H, ArÀ H), 7.55 (d, J = 2.0 Hz, 1H, ArÀ H), 6.94 (d, J = 8.3 Hz, 1H, ArÀ H), 5.98 (s, 1H, OH), 4.35 (q, J = 7.1 Hz, 2H, OCH 2 ), 3.95 (s, 3H, OCH 3 ), 1.38 (t, J = 7.1 Hz, 3H, CH 2 À CH 3 ). 13 (17), 107 (25). 1 H NMR of 6 c (400 MHz, CDCl 3 ) δ 11.09 (bs, 1H, OH), 7.44 (dd, J = 8.1, 1.5 Hz, 1H, ArÀ H), 7.03 (dd, J = 7.9, 1.5 Hz, 1H, ArÀ H), 6.81 (t, J = 8.0 Hz, 1H, ArÀ H), 4.40 (q, J = 7.1 Hz, 2H, OCH 2 ), 3.89 (s, 3H, OCH 3 ), 1.41 (t, J = 7.1 Hz, 3H, CH 2 À CH 3 ).…”

“…13 C NMR of 3 a (101 MHz, CDCl 3 ) δ = 153.1, 149.7, 134.7, 117.1, 116.2, 116.0, 68.2, 33.9. MS of 3 a (70 eV) m/z: 164 (25) [M] + , 110 (100), 55 (40). 1 H NMR of 3 b (400 MHz, CDCl 3 ) δ 6.97-6.92 (m, 1H, ArÀ H), 6.91-6.80 (m, 3H, ArÀ H), 5.90 (ddt, J = 17.1, 10.3, 6.7 Hz, 1H, CH = CH 2 ), 5.69 (s, 1H, OH), 5.20 (dq, J = 17.2, 1.6 Hz, 1H, = CH 2 ), 5.15 (dq, J = 10.2, 1.4 Hz, 1H, = CH 2 ), 4.11 (t, J = 6.5 Hz, 2H, OCH 2 ), 2.57 (qt, J = 6.6, 1.4 Hz, 2H, CHÀ CH 2 À CH 2 ).…”

“…Alternatively, the Ackerman group has recently demonstrated the indirect electrochemical hydroxylation of arenes catalyzed by transition-metals. [24,25] Selective direct electrochemical hydroxylation of electronrich arenes is still a difficult task. The desired hydroxylated product is much easier to oxidize than the starting compound, thus overoxidation and polymerization can easily occur leading to deposition on the electrode surface.…”

“…In the transformations described above, the substrate is directly oxidized on the electrode surface. Alternatively, the Ackerman group has recently demonstrated the indirect electrochemical hydroxylation of arenes catalyzed by transition‐metals [24,25] …”