Electrochemical Oxidation Cross Dehydrogenative Coupling of Enamines and Thiophenols for the Synthesis of Vinyl Sulfides

Abstract

A direct electrochemical oxidative cross dehydrogenative coupling reaction between enamines and thiophenols has been demonstrated. This strategy provides an effective, more economical, and environmentally friendly method to construct the C(sp2)‐S bond in the absence of chemical oxidants and transition metal catalysts. A variety of enamines and (hetero)aryl thiols are compatible with this transformation to afford the corresponding vinyl sulfides in moderate to excellent yields under undivided electrolytic cell conditions.

Recent Advances in Alkenyl sp2 C–H and C–F Bond Functionalizations: Scope, Mechanism, and Applications

“…More recently, Li and Xie followed this work in an attempt to expand the substrate scopes of this electrochemical protocol by employing a modified conditions with a carbon felt anode and a nickel plate cathode as the electrode materials. 606 Subsequently, Wu's group presented a general and highly efficient strategy for the vinylic β-C−H phosphorylation of enamines enabled by cost-effective cobaloxime catalysis under visible-light irradiation with hydrogen evolution (Scheme 379). 607 The reaction occurred under especially mild conditions and exhibited excellent functional group tolerance for both enamines and H-phosphine oxides, providing a concise route to a series of β-phosphinoyl products in 52−99% yield with modest Z-selectivity.…”

Tf2O‐Mediated Regioselective C(sp2)−H Sulfenylation of Enaminones Using Methyl Sulfoxides as Sulfur Sources

“…Inspired by this work, Loh, [10c] Prabhu, [10d] Maddani [10e] and Lei [10f] used the similar strategy to realize the formation of carbon‐sulfur bonds by the oxidative cross‐coupling of enaminones with thiophenols, respectively (Scheme 1, eq 3–6). Currently, Wan and Li went on to report the construction of C(sp 2 )−S bonds by KIO 3 /TEMPO oxidation, [10g] molecular iodine oxidation [10h] and electrochemical oxidation [10i] of enaminone derivatives. However, methyl sulfoxides as sulfur sources were utilized to participate regioselective C(sp 2 )−H sulfenylation of enaminones, which has not been reported yet.…”

Green and Practical Synthesis of Thioenamines and Chromones via Iodine-Catalyzed Cross-Dehydrogenation Coupling Reaction

“…1 H NMR (400 MHz, CDCl 3 ): δ 9.06 (s, 1H), 7.17 (d, J = 7.4 Hz, 1H), 7.13 (t, J = 7.6 Hz, 1H), 6.98 (t, J = 7.4 Hz, 1H), 6.83 (d, J = 7.7 Hz, 1H), 5.26 (s, 1H), 4.22−4.08 (m, 2H), 3.88 (s, 3H), 2.21 (s, 3H), 2.16 (s, 3H), 1.29 (t, J = 7.1 Hz, 3H). 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 169. 8, 166.3, 158.9, 146.1, 130.3, 129.3, 126.3, 123.5, 121.1, 81.5, 59.9, 55.9, 23.2, 17.8, 14.6…”

“…1 H NMR (400 MHz, CDCl 3 ): δ 13.62 (s, 1H), 7.31 (t, J = 7.8 Hz, 2H), 7.09 (t, J = 7.4 Hz, 1H), 7.03 (d, J = 8.8 Hz, 2H), 6.94 (d, J = 1.1 Hz, 1H), 6.92 (d, J = 0.9 Hz, 1H), 6.90 (d, J = 2.2 Hz, 1H), 6.88 (d, J = 2.1 Hz, 1H), 3.90 (s, 3H), 3.81 (s, 3H), 2.37 (s, 3H), 2.15 (s, 3H). 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 198. 5,167.3,156.8,146.3,135.4,128.1,127.9,127.4,126.9,126.5,122.6,120.4,91.0,68.8,28.0,22.8.…”

“…1 H NMR (600 MHz, CDCl 3 ): δ 8.96 (s, 1H), 7.20 (t, J = 12.0 Hz, 2H), 6.97 (t, J = 6.0 Hz, 1H), 6.85 (d, J = 6.0 Hz, 2H), 5.35 (s, 1H), 4.21 (q, J = 6.0 Hz, 2H), 3.62 (s, 3H), 2.08 (s, 3H), 1.19 (t, J = 6.0 Hz, 3H). 13 C{ 1 H} NMR (150 MHz, CDCl 3 ): δ 169. 2, 165.8, 157.5, 146.6, 127.8, 122.3, 120.5, 79.9, 63.4, 50.4, 22.0, 13.2 S-((E)-2-Amino-4-oxopent-2-en-3-yl) O-Ethyl (Z)-Phenylcarbonimidothioate (3ax).…”