Nitren‐Chemie in der organischen Synthese: noch in den Kinderschuhen?

Abstract

Stickstoff zählt zu den lebenswichtigen Elementen. Daher wird der Entwicklung von Synthesemethoden zur Einführung dieses Elements in Moleküle besondere Beachtung geschenkt. Nachdem Nitrene seit langem als sehr reaktive, doch unselektive Spezies bekannt waren, konnten sie kürzlich auch zur Bildung von C‐N‐Bindungen eingesetzt werden. Nun sind metallkatalysierte Methoden für die Synthese von Aminen durch Aziridierung von Alkenen oder C‐H‐Aminierung von Alkanen verfügbar. Die hier beschriebenen Ergebnisse zeigen, dass die Nitren‐Chemie für einen größeren Anwendungsbereich in der Synthese nutzbar wird und nicht auf diese beiden Reaktionen beschränkt bleibt.

Iridium‐Catalyzed Direct CH Amidation with Weakly Coordinating Carbonyl Directing Groups under Mild Conditions

“…To examine the above hypothesis, we screened various reaction conditions for the amidation of ethyl benzoate (1 a) with an equimolar amount of para-toluenesulfonyl azide (2 a) that are based on our recently developed procedures for CÀH amidation [9,10] using a {Cp*Ir III } catalyst system (Table 1; Cp* = pentamethylcyclopentadienyl). [11] When a silver salt, which is required for the generation of a cationic iridium species, was used as the sole additive (entry 1), no reaction occurred.…”

Rh(III)‐Catalyzed Phosphine Oxide Migration Reactions: Selective Synthesis of 3‐Phosphinoylindoles

“…Thus, Rh(OAc) 3 ·x H 2 Om ay react first with the aryl azide to form the rhodiumnitrene A by loss of N 2 . [16] Based on the experiment dataa bove and previous mechanistic studies, [5,14,16] we proposed that the cyclization occured from ac ommonc atalytic intermediate, [7] (Scheme4). Rh(OAc) 3 ·x H 2 Oc ould function as an itrogen atom transfer reagent.…”

Interconversion of Phosphinyl Radical and Phosphinidene Complexes by Proton Coupled Electron Transfer

“…[3,4] Free phosphinidenes (PR) could only very recently be sufficiently stabilized. [9] Thes carcity of catalytic PR-transfer might in part be attributed to alack of suitable oxidizing PR-transfer reagents, such as analogs of iminoiodane (ArI=NR) or azide (RN 3 ) nitrene sources.Primary phosphines are attractive precursors from athermochemical point of view due to lower intrinsic P À Hc ompared to N À Hb ond dissociation (free) energies (BD(F)Es;S cheme 1). [9] Thes carcity of catalytic PR-transfer might in part be attributed to alack of suitable oxidizing PR-transfer reagents, such as analogs of iminoiodane (ArI=NR) or azide (RN 3 ) nitrene sources.Primary phosphines are attractive precursors from athermochemical point of view due to lower intrinsic P À Hc ompared to N À Hb ond dissociation (free) energies (BD(F)Es;S cheme 1).…”