Geminale Vinyldiazide, IV¹⁾ Substituentenabhängige Konkurrenz zwischen 1,5‐ und 3,5‐Cyclisierung bei Vinylaziden; 1,2,3‐Triazole und 2H‐Azirine aus 3,3‐Diazido‐2‐cyanacrylsäure‐methylester und Aminen

Abstract

Die Umsetzung von 3,3-Diazido-2-cyanacryls$ure-methylester (5) mit Amincn 12 fuhrt primir zu zum Teil bemerkenswcrt stabilen Donor-substituierten Vinyladden 13, die durch 1.5-Cyclisirrung iiber die 4H-1,2,3-Triazole 14 1,2,3-Tria~ole 16 bilden. In speziellen Fallen konkurriert mit der 1.5-die 3.5-Cyclisierung der Vinylazide 13, die zu 2H-Azirinen 15 fuhrt.Wahrend 1,4-Diazabicyclo[2.2.2]octan (Dabco)') das Vinyldiazoniumsalz 1 a ausschliei3lich zu Diazoessigester entalkyliert'), wird 2-Chlor-2-(4-methoxyphenyl)-l-ethendiazonium-hexachloroantimonat (1 b) von Dabco deprotoniert, und man isoliert Chlor(4-methoxypheny1)acetylen (4b)'). Vorstufe fur das Vinyliden 3b ist das Diazoethen 2b6). Rcaction of methyl 3.3-diazido-2-cyanoacrylate (5) with aniincs I2 primarily leads to somc remarkably stable donor-substitutcd vinyl azidcs 13. These undcrgo a I.5-cyclizatiori and form via 4tf-1,2,3-triazoles 14 1,2,3-triazoles 16. In special cases herewith 3 -3 5 cyclization of 13 competes giving 2H-azirines 15.Methanol'). Ob fur die Bildung von 8 das Diazoalken 6 als Zwischenstufe auftritt, ist bisher nicht eindeutig geklart. Bei der thermischen Zersetzung von 5 in Methanol isoliert man 2-(Cyanimino)-2-methoxyessigsaure-methylester (9)7). Dabei entsteht aus 5 unter Nz-Eliminierung wahrscheinlich zunachst das Azidoazirin ll*), das unter erneuter N2-Abspaltung und Umlagerung den Ester 10 liefert, der schliel3lich mit Methanol zu 9 reagiert.Vollig anders verhalt sich 3,3-Diazido-2-cyanacrylsauremethylester (5) in Dichlormethan bzw. Ether in der Kalte.

Synthesis and Chemistry of Organic Geminal Di- and Triazides

“…At 70 °C and 50 °C, respectively, 73 and 74 explode spontaneously. Analytical confirmation of the structures was obtained from their infrared and NMR spectra as well as from mass spectrometry in the case of methyl 3,3-diazido-2-cyanoacrylate ( 73 ) [95,96,98,102]. 2-(Diazidomethylene)malononitrile ( 75 ) is described as an orange liquid.…”

“…Formally, this must be seen as a 1,4-addition followed by elimination of hydrazoic acid. The resulting vinyl azides 92 can, in most cases, be isolated in good yields as crystalline solids [98,102,104,105,106,107,108,110,111]. Because of the thermal instability of geminal vinyl azides 83 , this reaction has to be performed at temperatures below −20 °C.…”

“…Otherwise, the N -cyanoimine 86 (Scheme 17) would be generated before an intermolecular reaction can take place. As nucleophiles, primary [98,102,104,105,107,108,110,111] and secondary [102,107,111] amines, diamines [106,108,111] and hydrazines [98] were tested. With diamines, the substitution occurs either on two different molecules of the diazide 73 generating vinyl azides 93 [106,108,111] or on the same molecule delivering cyclic products 94 [106].…”

“…The reaction of simple amines with geminal vinyl diazides results in the substitution of one azide group, eventually affording vinyl azide 92 (Scheme 18). This vinyl azide species 92 was shown to undergo many different consecutive reactions giving access to a broad spectrum of nitrogen-containing heterocycles like tetrazolylidenes [98,106,108,110,111], imidazolylidenes [110,111], oxazoles [106,107,108,110], 1,2,3-triazoles [102,111], azirines [102], 2-methylidene-3,4,5,6-tetrahydropyrimidines [106] and 2-methylidene-2,3-dihydroperimidines [106]. The definite outcome of the reaction strongly depends on the substitution pattern of the vinyl azide 92 and the precise reaction conditions [98,102,103,106,107,108,110,111].…”

Structure of methyl (E)-2-cyano-2-(1-phenyl-4,5-dihydro-1H-tetrazol-5-ylidene)acetate

“…Depending on the substituents R/R 1 and the reaction conditions, either stable 1,2,3-triazoles are formed v/a the 4H-1,2,3-triazoles (2) or 2H-azirines (3) are generated with elimination of nitrogen (Saalfrank, Ackermann, Fischer & Wirth, 1987).…”