Straightforward Synthesis of Ethers: Metal‐Free Reductive Coupling of Tosylhydrazones with Alcohols or Phenols

Abstract

Einfach zum Ether: Erhitzen von Lösungen, die ein Tosylhydrazon und ein Phenol oder einen anderen Alkohol enthalten, in Gegenwart von K2CO3 ergibt die entsprechenden Arylalkyl‐ und Alkylalkylether (siehe Schema; MW=Mikrowellen, Ts=Tosyl). Die Reaktion kommt als neue Methode für die reduktive Veretherung von Carbonylverbindungen in Betracht.

Nickel‐ and Cobalt‐Catalyzed Direct Alkylation of Azoles with N‐Tosylhydrazones Bearing Unactivated Alkyl Groups

“…[9] An initial base-assisted direct nickelation of a heteroarene [10] provides a heteroaryl nickel species A. On the other hand, the N-tosylhydrazone is converted in situ to the corresponding diazo compound B with concomitant elimination of the Ts group by the action of a base.…”

“…Our working hypothesis is inspired by our previous success in the nickel-catalyzed direct alkylation of azoles with primary alkyl halides [4f] and recent developments in the use of N-tosylhydrazones in cross-coupling reactions (Scheme 1). [9] An initial base-assisted direct nickelation of a heteroarene [10] provides a heteroaryl nickel species A. On the other hand, the N-tosylhydrazone is converted in situ to the corresponding diazo compound B with concomitant elimination of the Ts group by the action of a base.…”

Luxury of N‐Tosylhydrazones in Transition‐Metal‐Free Transformations

“…[91] This reductivee therification of carbonyl compoundsfacilitated insertion of the emergent carbenei nto the O À Hb ond. [91] This reductivee therification of carbonyl compoundsfacilitated insertion of the emergent carbenei nto the O À Hb ond.…”

“…Following the seminal report by Va ldØs [91] andt he abovep rotocol, various research groups extended the construction of diverse thioethers by exploiting a range of thiols.I n2 016, Zhang andc o-workers demonstrated the synthesis of ferrocenyl-based thioethers 169 via am etal-free reductive coupling of ferrocenyl tosylhydrazones 168 and thiols (Scheme 86). [97] Notably,t he 1,10-ferrocenyl diketone-derived N-tosylhydrazone with various thiophenols afforded the corresponding dithioethers.I na ddition,t he benzimidazolyl-derived thioether wasc hosen for ac hemosensor study,w hich showedavery good recognition towards Hg 2+ + ion via optical and electrochemical signals.…”

Metal‐Free Ring‐Expansion Reaction of Six‐membered Sulfonylimines with Diazomethanes: An Approach toward Seven‐Membered Enesulfonamides

“…[9a] Fort hese reasons,t he metal-free reaction is highly desirable,a nd indeed, significant progress has been made in the past years. [6,[8][9][10] Themetal-free coupling reactions of diazo compounds generated in situ from Ntosylhydrazones under basic reaction conditions (Bamford-Stevens reaction) [7] have appeared in the recent literature. [8] In pioneering studies,B arluenga, Va ldØs,a nd co-workers discovered metal-free reductive cross-coupling of boronic acids, [9a] phenols,and alcohols [9b] with N-tosylhydrazones.The group of Wang also reported ametal-free reaction to convert N-tosylhydrazones into pinacol boronates.…”