Aziridinimines, Diaziridinimines, Diaziridinones, and Carbodiimides by Photolysis of 2‐Tetrazolines

Quast, Helmut; Bieber, Lothar W.

doi:10.1002/anie.197504281

Cited by 61 publications

(19 citation statements)

References 15 publications

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“…The photochemically induced opening of the tetrazole ring has been found to be a common process. [22][23][24][64][65][66][67][68][69] As mentioned before, unsubstituted tetrazole easily eliminates molecular nitrogen, leading to production of nitrilimine, which then undergoes secondary photoreactions, such as isomerization to carbodiimide, cyanamide, or a hydrogen cyanide/nitrene complex. 23 The proposed reaction pathways resulting from irradiation of 5EPT are schematically shown in Scheme 1, and the complete list of bands due to the products of photolysis is presented in Tables 2 and 3.…”

Section: νC-o/νndc νC-n νNdc/νn-c νN-n δ(T-ring 2) νC-c/νo-c δChmentioning

confidence: 99%

Photochemistry and Vibrational Spectra of Matrix-Isolated 5-Ethoxy-1-Phenyl-1H-Tetrazole

et al. 2007

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A combined matrix isolation FT-IR and theoretical DFT(B3LYP)/6-311++G(d,p) study of the molecular structure and photochemistry of 5-ethoxy-1-phenyl-1H-tetrazole (5EPT) was performed. A new method of synthesis of the compound is described. Calculations show three minima, very close in energy and separated by low-energy barriers (less than 4 kJ mol -1 ), in the ground-state potential energy profile of the molecule. The method of matrix isolation enabled the reduction of the number of populated conformational states in the experiment at low temperature due to the effect known as conformational cooling. As a result, the spectrum of the as-deposited matrix of 5EPT closely matches that of the most stable conformer predicted theoretically, pointing to the existence of only this conformer in the low-temperature matrixes. In this structure, the dihedral angle between the two rings, phenyl and tetrazole, is ca. 30°, whereas the ethyl group stays nearly in the plane of the tetrazole ring and is as far as possible from the phenyl group. In situ UV irradiation (λ > 235 nm) of the matrix-isolated 5EPT induced unimolecular decomposition, which led mainly to production of ethylcyanate and phenylazide, this later compound further reacting to yield, as final product, 1-aza-1,2,4,6-cycloheptatetraene. Anti-aromatic 3-ethoxy-1-phenyl-1H-diazirene was also observed experimentally as minor photoproduct, resulting from direct extrusion of molecular nitrogen from 5EPT. This species has not been described before and is now characterized by infrared spectroscopy for the first time.

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Section: νC-o/νndc νC-n νNdc/νn-c νN-n δ(T-ring 2) νC-c/νo-c δChmentioning

confidence: 99%

Photochemistry and Vibrational Spectra of Matrix-Isolated 5-Ethoxy-1-Phenyl-1H-Tetrazole

et al. 2007

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“…28 Analysis of the literature reveals that, through a careful selection of the solvent and other reaction conditions, the photofragmentation of some derivatives of tetrazole may be tuned to grant selectivity and high yield, affording stable and synthetically useful photoproducts that may be isolated and stored, or trapped in the reaction media. A diversity of photoproducts such as 9H-pyrimido(4,5-b)indoles, 24 diaziridinones, 16,25 iminoaziridines, 26,27 carbodiimides, 22,25 oxazines, 14 benzimidazolones 22 and pyrimidinones 10,11 may be obtained from photolysis of tetrazole derivatives in solution. Of the 7 classes mentioned, 3 (diaziridinones, benzimidazolones and pyrimidinones) result from photolysis of 1,4-disubstituted-1,4-dihydro-5H-tetrazol-5-ones (tetrazolones), illustrating their versatility as starting materials for the preparation of other scaffolds and the relevance of a deep investigation of the photochemistry of this particular class.…”

Section: Introductionmentioning

confidence: 99%

Photochemistry of 1-allyl-4-aryltetrazolones in solution; structural effects on photoproduct selectivity

Ismael

Serpa

Cristiano

2013

Photochem Photobiol Sci

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The photochemistry of tetrazolones derived from the carbocyclic allylic alcohols cyclohex-2-enol and 3-methylcyclohex-2-enol and from the natural terpene alcohol nerol was investigated in solution with the aim of assessing the effect of solvent and of structural constraints imposed by bulky allylic moieties on photoproduct selectivity and stability. Photolysis of tetrazolones derived from nerol and cyclohex-2-enol afforded the corresponding pyrimidinones as major products through a pathway that appears to be similar to that proposed for other 1-allyl-4-phenyl-1,4-dihydro-5H-tetrazol-5-ones derived from acyclic and unhindered allylic alcohols previously investigated but photolysis of the tetrazolone derived from the bulkier 3-methylcyclohex-2-enol 4c leads to formation of a benzimidazolone, indicating that, in this case, cyclization of the biradical formed upon extrusion of N 2 involves the phenyl substituent and not the allylic moiety. Theoretical calculations (DFT(B3LYP)/3-21G*) were conducted to support the interpretation of the experimental results and mechanistic proposals. Laser flash photolysis experiments were conducted with the aim of clarifying the nature of the intermediate involved in the primary photocleavage process.

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“…[10] We disclose here the detecsodium hydride yields the yellow 5-alkylidenedihydrotetrazoles 2. [2] [3] [4] Irradiation of 2 with UV light results in a tion by EPR spectroscopy of a novel nitrogen analogue of trimethylenemethane, i.e. the triplet diazatrimethylenemethclean extrusion of molecular nitrogen and the quantitative, diastereoselective formation of (E)-iminoaziridines 3 which ane 23.…”

mentioning

confidence: 99%

“…Furthermore, the results of this work broaden the basis for the definition of scope and limitation of the photoundergo (E) v (Z) equilibration at room temperature. [2] [5] [6] Iminoaziridines with unsaturated substituents, i.e. 3dϪf, chemical synthesis of iminoaziridines from 5-alkylidenedihydrotetrazoles.…”

mentioning

confidence: 99%

“…The progress of the deprotonation reaction was indicated by the evolution of hydrogen and the development of a yellow colour which is characteristic for alkylidenedihydrotetrazoles. [2] [3] [4] A number of runs, performed with 6a, served to optimise the experimental protocol. Deprotonation with sodium or potassium hydride in diethyl ether or tert-butyl methyl ether was very slow in the absence of 18-crown-6.…”

mentioning

confidence: 99%

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Photoextrusion of Molecular Nitrogen from Annulated 5-Alkylidene-4,5-dihydro-1H-tetrazoles: Annulated Iminoaziridines and the First Triplet Diazatrimethylenemethane

Quast¹,

Fuss

Nüdling

1998

Eur. J. Org. Chem.

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Deprotonation of the annulated tetrazolium salts 4, 6, 8, 10, and 12 with sodium or potassium hydride yields the alkylidenedihydrotetrazoles 5, 7, 9, 11, and 13, respectively. While 5a and b are unstable, even in solution at low temperatures, 7, 9, 11, and 13 form yellow oils that are distilled under high vacuum. − Irradiation of solutions of 7, 9, and 11 in [D8]toluene at −60°C yields, besides molecular nitrogen, annulated iminoaziridines that have an exocyclic CN double bond, i.e. 14, 16, and 18, respectively. In addition, an equal amount of the isomer 19 with the endocyclic CN double bond is formed from 11. On thermolysis, 14, 16, and 18 undergo [2 + 1] cycloreversion into methyl isocyanide and the cyclic imines 15, 17, and 20, respectively. By contrast, 19 rearranges thermally to yield 18. While the doubly bridged alkylidenedihydrotetrazole 13a affords only unidentified decomposition products on photolysis, its methyl homologue 13b is converted into the hexahydronaphthyridine 22 which is also formed on thermolysis. − Irradiation of 13b in a 2‐methyltetrahydrofuran or butyronitrile matrix at 77 K yields a triplet diradical showing a four‐line EPR spectrum centred at 3362 G and a half‐field transition (at 1669 G) with a hyperfine structure. The zero‐field splitting parameters |D‐hc| = 0.031 cm−1 and |E‐hc| = 0.0014 cm−1 are obtained by simulation of the EPR spectrum. The signal‐carrier is assigned the diazatrimethylenemethane structure 23 on the basis of the close similarity between its EPR spectrum and those of trimethylenemethane (28) and tris(N‐methylimino)methane (29). − Structural features are discussed that are responsible for the observed differences between the photochemical pathways.

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Aziridinimines, Diaziridinimines, Diaziridinones, and Carbodiimides by Photolysis of 2‐Tetrazolines

Cited by 61 publications

References 15 publications

Photochemistry and Vibrational Spectra of Matrix-Isolated 5-Ethoxy-1-Phenyl-1H-Tetrazole

Photochemistry and Vibrational Spectra of Matrix-Isolated 5-Ethoxy-1-Phenyl-1H-Tetrazole

Photochemistry of 1-allyl-4-aryltetrazolones in solution; structural effects on photoproduct selectivity

Photoextrusion of Molecular Nitrogen from Annulated 5-Alkylidene-4,5-dihydro-1H-tetrazoles: Annulated Iminoaziridines and the First Triplet Diazatrimethylenemethane

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