Recent advancements in dehydrogenative cross coupling reactions for CC bond formation

Cu‐Catalyzed Cross‐Dehydrogenative ortho‐Aminomethylation of Phenols

“…[2] Thel atter methods are increasingly popular due to atom-and step-economy considerations,which often lends them an inherently sustainable character.Therein, the field of cross-dehydrogenative couplings (CDCs) is particularly attractive because this concept avoids pre-activation steps for both coupling partners. [3] Thedevelopment of useful intermolecular CDCs,h owever,i sa ssociated with considerable challenges,such as regioselectivity or undesired homocoupling processes.I no rder to intercept the oxidation of the most electron-rich coupling partner into atrue heterocoupling process,o ne can resort to substrate bias (i.e., sterics). [4] Alternatively,o ne can utilize metal catalysis in order to control the various competing oxidation pathways, and thereby escape the narrow substrate specificity often imposed by metal-free systems.H erein, we propose such as trategy through the Cu II -catalyzed cross-dehydrogenative ortho-aminomethylation of phenols [5,6] with aniline derivatives (Scheme 1a nd Scheme 2).…”

Direct oxidative C(sp3)─H/C(sp2)─H coupling reaction using recyclable Sr‐doped LaCoO3 perovskite catalyst

“…In addition, MS analysis indicated the presence of 2,2,6,6‐tetramethyl‐1‐(tetrahydrofuran‐2‐yloxy)piperidine as an intermediate in the reaction mixture (Scheme a). On the basis of all these results and previous reports, a reaction pathway is proposed as described in Scheme b. Initially, tert ‐butoxy radical would be formed through the cleavage of DTBP with the assistance of the perovskite catalyst.…”

Intramolecular hydride transfer onto arynes: redox-neutral and transition metal-free C(sp3)–H functionalization of amines

“…10 equivalents of acetonitrile, see entry 14) afforded 2 in a respectable 35% yield, which hinted at the potential to expand this method to more valuable pronucleophiles in the future. However, as the 3 : 1 volumetric ratio of DME : acetonitrile afforded the best yields and represented a good improvement in pronucleophile loading compared to the majority of CDC processes, 4 especially those involving this less common pronucleophile, 22 these conditions were selected for the study.…”

“…The direct functionalization of C–H bonds offers a wealth of potential benefits to synthetic chemists, 1 with significant progress having been made in recent decades. 2 Activation of C(sp 3 )–H bonds α- to heteroatoms is particularly appealing, 3 as evidenced by the burgeoning area of cross-dehydrogenative coupling (CDC) reactions, 4 whereby certain substrates, especially amines, are functionalized using a sacrificial external oxidant and generally in the presence of a transition metal catalyst. 5 α-Functionalization of amines has also received considerable recent interest through the development of redox-neutral processes 6 that exploit the propensity of tertiary amines to undergo 1,5-hydride transfer onto a tethered acceptor, 7 most commonly electron-deficient alkenes ( Scheme 1a ).…”