Cobaltaelectro-catalyzed oxidative allene annulation by electro-removable hydrazides

Abstract

A sustainable and highly efficient cobaltaelectro-catalyzed C–H/N–H functionalization with allenes was developed featuring electro-reductive hydrazide cleavage.

Metallaphotoredox-catalyzed C–H activation: regio-selective annulation of allenes with benzamide

“…Various noble second-and third-row transition metals such as Pd [26][27][28][29][30][31][32], Ir [33], Rh [34][35][36][37][38][39][40] and Ru [41], have been employed for the preparation of cyclic scaffolds from simple, nonfunctionalized acyclic starting materials. Moreover, the rst-row transition metals, such as Mn [42][43][44][45][46][47], Fe [48], Ni [49][50][51][52][53] and Co [54][55][56][57][58][59][60][61][62][63], have been recognized as cheap, environmentally friendly and reactively effective catalysis for C − H functionalization with allenes. Particularly, cobalt-catalyzed regioselective intermolecular cyclization reactions of arylamides or alkenylamides with allenes were independently reported by the group of Cheng [56][57][58], Volla [59], Rao [60], Zhai [61], and Ackermann [62]…”

“…Moreover, the rst-row transition metals, such as Mn [42][43][44][45][46][47], Fe [48], Ni [49][50][51][52][53] and Co [54][55][56][57][58][59][60][61][62][63], have been recognized as cheap, environmentally friendly and reactively effective catalysis for C − H functionalization with allenes. Particularly, cobalt-catalyzed regioselective intermolecular cyclization reactions of arylamides or alkenylamides with allenes were independently reported by the group of Cheng [56][57][58], Volla [59], Rao [60], Zhai [61], and Ackermann [62][63], which provide rapid synthetic routes for diverse isoquinolin scaffolds (Scheme 1a). Generally, stoichiometric amounts of metal oxidants (Ag 2 CO 3 , Mn(OAc) 2 , Mn(OAc) 3 , etc.…”

“…), which could re-oxidize low valent cobalt and complete the reaction cycle, were commonly employed in these reported cobaltcatalyzed annulation reactions of arylamides with allenes (Scheme 1a). Recently, Ackermann group disclosed an electrochemical C − H activation with allenes which enabled the high valent cobalt regeneration under the anodic oxidation (Scheme 1a) [62][63].…”

Copper-Mediated Oxidative C−H/N−H Activations with Alkynes by Removable Hydrazides

“…[36], was identified as a powerful removable bidentate directing group, which found widespread application in various cobalt catalyzed C−H activations [37][38][39][40]. Thus, our group also accomplished a set of electrochemical cobalt-catalyzed C−H activations with the MHP auxiliary [41][42][43][44]. In continuation of studies on sustainable 3d transition metal-catalyzed C−H activation [41][42][43][44][45][46][47][48][49], we have now discovered a robust copper-promoted oxidative C−H/N−H functionalization with terminal alkynes (Figure 1d).…”

Metallaphotoredox-Catalyzed C−H Activation: Regio-Selective Annulation of Allenes with Benzamide

“…Various noble second-and third-row transition metals such as Pd [26][27][28][29][30][31][32], Ir [33], Rh [34][35][36][37][38][39][40] and Ru [41], have been employed for the preparation of cyclic scaffolds from simple, nonfunctionalized acyclic starting materials. Moreover, the rst-row transition metals, such as Mn [42][43][44][45][46][47], Fe [48], Ni [49][50][51][52][53] and Co [54][55][56][57][58][59][60][61][62][63], have been recognized as cheap, environmentally friendly and reactively effective catalysis for C − H functionalization with allenes. Particularly, cobalt-catalyzed regioselective intermolecular cyclization reactions of arylamides or alkenylamides with allenes were independently reported by the group of Cheng [56][57][58], Volla [59], Rao [60], Zhai [61], and Ackermann [62]…”