- Isoquinolinium N-Arylimides and Strained Cycloalkenes [1]
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In contrast to common alkenes and enol ethers, the angle-strained double bonds of norbornene, dimethyl norbornadiene-2,3-dicarboxylate, and acenaphthylene undergo [3+2] cycloadditions with isoquinolinium N-arylimides. The structures of the crystalline adducts have been elucidated from their 1H nmr spectra.
- Temme, Robert,Huisgen, Rolf
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- Structural verification of a tetrahydrotetrazole compound
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Tetrahydrotetrazoles are five-membered-ring heterocycles containing four contiguous saturated nitrogen atoms. Very few examples of such compounds have been reported in the literature. Our previous attempt at the synthesis of a member of this class of compound suggested that the N - N bonds may be more labile than expected. This finding raised the question as to whether the structures of any of the previously reported tetrahydrotetrazoles had been properly assigned. We have reproduced the synthesis of a reported tetrahydrotetrazole, namely 1,2-di-tert-butyl 3-phenyl-1H,2H,3H,10bH-[1,2,3,4]tetrazolo[5,1-a]isoquinoline-1,2-dicarboxylate, C25H30N4O4, and have now confidently confirmed its structure via X-ray crystallography. However, while sufficiently stable in the crystal phase, we discovered that it remains very labile in solution (having a half-life of only 15min at 20°C in CDCl3). A tentative reaction pathway for its dissociation based on 1H NMR spectral evidence is provided.
- Breton, Gary W.,Hahn, Lauren A.,Martin, Kenneth L.
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p. 1208 - 1212
(2019/09/18)
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- Isoquinolinium N-arylimides and some cycloadditions to heterocumulenes
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The red isoquinolinium N-arylimides 19-23 are azomethine imines of which the C=N bond is part of an aromatic ring. The N-(4-nitrophenyl)imide 22 and the N-(2-pyridyl)imide 23 were obtained crystalline; in solution the latter equilibrates with the hexahydrotetrazine 24 as its dimer. The N-phenyl-imide 19 is not stable; an isolated solid appears to be a tetramer. Generated by deprotonation of 11-13, the N-arylimides 19-21 undergo in situ cycloadditions to carbon disulfide, phenyl isocyanate, phenyl isothiocyanate, and diphenylketene. The storable CS2 adduct 29 offers a neutral source of the N-phenylimide 19, since a cycloreversion equilibrium is established in solution.
- Bast, Klaus,Behrens, Matthias,Durst, Toni,Grashey, Rudolf,Huisgen, Rolf,Schiffer, Reinhard,Temme, Robert
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p. 379 - 385
(2007/10/03)
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