Cobalt‐Catalyzed Directed sp² C−H Acetoxylation of Arenes Employing Mn(OAc)₃ ⋅ 2H₂O as Acetoxy Source

Abstract

A cobalt-catalyzed sp 2 CÀH acetoxylation of amides having 8-aminoquinoline as a directing group has been achieved using manganese (III) acetate both as an oxidant and an acetoxy source. Operational simplicity, broad range of functional group tolerance, use of an earth abundant first row transition metal, and, most importantly, exploitation of an unprecedented acetoxy source are the key features. The method is scalable and does not require any additive. The mechanism of the reaction has been established by conducting a series of experiments.

Diastereoselective Spirocyclization of Cyclic N-Sulfonyl Ketimines with Nitroalkenes via Iridium-Catalyzed Redox-Neutral Cascade Reaction

“…Recently, we have developed a mild and efficient Ir­(III)-catalyzed C–H amidation of N -sulfonyl ketimines . In continuation of our interest in transition-metal-catalyzed C–H functionalization reactions, herein we wish to report an Ir­(III)-catalyzed diastereoselective spiroannulation of N- sulfonyl ketimines and α,β-unsaturated nitro olefins under a redox-neutral process.…”

Cobalt‐Catalyzed C(sp2)−O Bond Formation by Directing Group Assisted C−H Activation

“…Deb et al reported a cobalt(II)-catalyzed CÀ H acetoxylation process using manganese triacetate as the source of the acetoxyl group (Scheme 6). [22] As in the aforementioned study by Chatani et al, amides containing 8-aminoquinoline directing groups were used. Aromatic and heteroaromatic amides were demonstrated to be applicable to this CÀ O bond-forming reaction, providing the desired acetoxylated amides in moderate to excellent yields (15 a-15 i).…”

“…Next, intramolecular single electron transfer (SET) of intermediate 19-A produces the cationic radical intermediate Co(II) 19-B, which undergoes a second oxidation by a silver oxidant to form Co(III) intermediate 19-C. A similar process has been reported by Gui et al [27] The intermediate In this study, the suggested reaction mechanism is different from that suggested in previous studies. [20,22,24] Therefore, another possible process involving the coordination of cobalt species followed by CÀ H activation through the CMD process could not be ruled out.…”

Advances in Transition-Metal-Catalyzed C–H Bond Oxygenation of Amides

“…In 2018, Deb and co-workers reported the Co-catalyzed ortho-C(sp 2 )-H acetoxylation of unactivated benzamides using Mn(OAc) 3 •2H 2 O as an acetoxy source (Scheme 7a). 19 The methodology was applied to a wide range of substrates.…”