Triazene: vielseitige Verbindungen für die organische Synthese

Kimball, David B.; Haley, Michael M.

doi:10.1002/1521-3757(20020916)114:18<3484::aid-ange3484>3.0.co;2-b

“…However, they are not stable under the prevailing reaction conditions. It is a case of nonstabilized triazenes 231. In the presence of Lewis acids, they open to amidodiazonium betaines 188 , which according to the structure of the addition product either rearrange with migration of the substituents (path b) or ring contraction occurs (path a).…”

Section: Reactions Of Organic Azidesmentioning

confidence: 99%

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

Bräse

¹

,

Gil

²

,

Knepper

³

et al. 2005

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Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aubé rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

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“…However, the research in this area is still rare because the phenyl cation is unstable, which limits its application in organic synthesis. Herein, based on the generation of highly activated phenyl cation intermediates, we describe a BF 3 ·OEt 2 -promoted intramolecular amination and oxylation strategy for the direct formation of dibenzofurans and carbazoles from biaryl triazenes [19] under Lewis acid conditions (path d, Scheme 2).Initially, we treated amino-triazene 2 with BF 3 ·OEt 2 in DMF, leading to the formation of the desired carbazole 4 a in 50 % yield (Scheme 3). Interestingly, when we treated ditriazene 3 a (R 1 = R 2 = Bn) with BF 3 ·OEt 2 in EtOH, the yield of the formation of carbazole 4 a increased to 80 %.…”

mentioning

confidence: 99%

“…However, the research in this area is still rare because the phenyl cation is unstable, which limits its application in organic synthesis. Herein, based on the generation of highly activated phenyl cation intermediates, we describe a BF 3 ·OEt 2 -promoted intramolecular amination and oxylation strategy for the direct formation of dibenzofurans and carbazoles from biaryl triazenes [19] under Lewis acid conditions (path d, Scheme 2).…”

mentioning

confidence: 99%

Lewis Acid‐Promoted Synthesis of Unsymmetrical and Highly Functionalized Carbazoles and Dibenzofurans from Biaryl Triazenes: Application for the Total Synthesis of Clausine C, Clausine R, and Clauraila A

Yang

¹

,

Zhou

²

,

Wang

³

et al. 2011

Chemistry A European J

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“…[10b] The triazene precursors can be prepared by the addition of nitrogen-based nucleophiles to aryl diazonium salts or by the addition of organometallic species to azides with subsequent trapping of the resulting triazenyl anion with electrophiles, the former being the more popular approach. [12] These methods have limited synthetic utility. Herein we report a convenient synthetic route to alkyl acyl triazenes that uses azides as substrates and employs mild conditions; furthermore, we disclose that these acyl triazenes undergo thermal or base-catalyzed fragmentation in situ to form diazo compounds in high yield.We reasoned that triazenes (and thus diazo compounds) might be accessible from the phosphazides produced by the highly chemoselective reaction of a phosphine and an azide.…”

mentioning

confidence: 99%