Intramolecular 1,5-C(sp³)–H radical amination via Co(ii)-based metalloradical catalysis for five-membered cyclic sulfamides

Abstract

Synthesis of strained five-membered cyclic sulfamides has been achieved for the first time by intramolecular 1,5-C(sp3)–H amination via Co(ii)-based metalloradical catalysis.

Sulfamate Esters Guide Selective Radical‐Mediated Chlorination of Aliphatic C−H Bonds

“…To our knowledge, there are no general strategies for aliphatic γ-C–H functionalization guided by a masked alcohol. [4,5] Herein described are the first experiments to demonstrate that sulfamate esters [6,7] can mediate 1,6-hydrogen-atom transfer (HAT) processes to guide the light-promoted chlorination of unactivatedγ-C(sp 3 )–H centers.…”

“…[14] By contrast, we anticipate sulfamate esters may be capable of mediating 1,6-HAT processes, which are rare [15] as they are expected to proceed through seven-membered transition states, which are often kinetically disfavored. [16] We hypothesize that sulfamate esters enable 1,6-HAT because their elongated O–S and S–N bonds (∼1.58 Å) and compressed O–S–N bond angles (∼103°) [17] geometrically favor a seven-membered ring transition state for C–H abstraction. The site-selectivity available through these reactions complements that achieved using traditional HLF chlorination transformations, [18] alternative guided chlorination methods, [19] or site-selective intermolecular [20] chlorination processes.…”

Progress in Co-Catalyzed C-H Amination

“…图式 17 分子间竞争实验 Scheme 17 Intermolecular competition experiment 2016 年, Sundararaju 课题组 [27] 报道了钴催化喹啉 40 2016 年, 张小祥课题组 [28]…”

Sulfamate Esters Guide Selective Radical‐Mediated Chlorination of Aliphatic C−H Bonds

“…[31,32] Furthermore,t he directed chlorination reaction overcomes the innate site selectivity that arises from inductive deactivation in unguided oxidation processes.Inunguided CÀ Hf unctionalization reactions,p roximity to inductively electron-withdrawing groups deactivates CÀHb onds to oxidation. This phenomenon is evident when 3,7-dimethyloctanol is masked with an electron-withdrawing group,a nd engages in undirected fluorination, [33] oxygenation, [34] amination, [35] azidation, [36] or trifluoromethylthiolation [37] processes that functionalize C (7) in preference to C(3). By contrast, the sulfamate ester guided chlorination installs chlorine at the electronically deactivated C(3) position (entries 2-3).…”

“…Ah ydroxy group is attractive as ad irecting moiety because alcohols are common within readily available small molecules.T oo ur knowledge,t here are no general strategies for aliphatic g-C À Hf unctionalization guided by amasked alcohol. [4,5] Described herein are the first experiments to demonstrate that sulfamate esters [6,7] can mediate 1,6-hydrogen-atom transfer (HAT) processes to guide the light-promoted chlorination of unactivated g-C(sp 3 )ÀHc enters.…”