Oxidative cross-coupling: an alternative way for C–C bond formations

Oxidative R1–H/R2–H Cross-Coupling with Hydrogen Evolution

“…Over the past decade, developments in C–H activation allow the construction of C–C and C–X bonds from readily available substrates. Oxidative R 1 –H/R 2 –H cross-coupling has been considered an ideal way for constructing new chemical bonds. − However, sacrificial chemical oxidants are generally required to remove the hydrogen atoms in the bond formation processes. Stoichiometric amounts of hypervalent metal salts, organic halides, and peroxides are used in most cases (Scheme b).…”

Access to Polycyclic Thienoindolines via Formal [2+2+1] Cyclization of Alkynyl Indoles with S8 and K2S

“…On the basis of previous reports, we speculated that the deep red color was due to the formation of a long-chain S n 2– intermediate via the reaction of S 2– with S 8 and that this intermediate was then transformed into the dark blue key intermediate S 3 •– . Furthermore, treatment of the mixtrue of 1a and 1,4-diphenylbuta-1,3-diyne under standard condition led to the detection of 2,5-diphenylthiophene by ESI-MS, which indicated the involvement of S 3 •– in this reaction . Therefore, we propose that 2a formed by means of the S 3 •– -initiated pathway shown in Scheme .…”

“…Only a few syntheses of these compounds have been reported, despite the fact that they may have interesting medicinal properties, as suggested by the prevalence of these subunits in natural products with a broad spectrum of biological activities . Recently, Lei’s group reported the synthesis of 2,5-substituted thiophenes by means of [4+1] cycloaddition reactions of 1,3-diynes mediated by S 3 •– generated in situ from S 8 and a base . More recently, Ji’s group synthesized benzothiazine, thiophene, and 2-benzylidenetetrahydrothiophene derivatives by means of [5+1], [1+2+2], and [1+3+1] cycloaddition reactions involving S 3 •– generated in situ from K 2 S .…”

Electrochemical Oxidative Cross-coupling with Hydrogen Evolution: A Green and Sustainable Way for Bond Formation

“…1,2 Oxidative crosscoupling provides a new method for constructing chemical bonds. [3][4][5][6][7][8][9][10][11][12][13] Over the past decade, oxidative R 1 -H/R 2 -H cross-coupling has been developed as one of the most straightforward ways for constructing new chemical bonds. [14][15][16][17][18] This reaction protocol uses readily available starting materials without substrate prefunctionalization, which dramatically shortens the synthetic steps.…”