Synthesis and isomerization of the 3,4,12,12a-tetrahydro-2,6- -[1,3]oxazino[2,3-b] [1,3,4]benzotriazepin-7-one ring system

Gál, Melinda; Pallagi, István; Sohár, Pàl; Fülöp, Vilmos; Kàlmán, Alajos

doi:10.1016/s0040-4020(01)81030-9

Cited by 4 publications

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“…The signal at 3.30 ppm has cross-peaks with the carbon resonances at 38.8 (in the 2D HETCORR spectrum) and 172.7 ppm (in the 2D LR HETCORR spectrum), assigned to the (N-4)-methyl and C-5 of the ring form, respectively. The 1 H and 13 C NMR data for the ring conformer of 1 agree closely with those observed by Gál et al . All conformational energy differences (Δ G °) between the ring and open-chain forms were estimated from the integrals (I) of the (N-4)-methyl and/or (C-2)-methyl protons, using the equation Δ G ° = − RT ln K , where K = I (major form)/ I (minor form) for 1 − 4 (see Tables and ).…”

Section: Resultssupporting

confidence: 77%

Conformational Complexity in Seven-Membered Cyclic Triazepinone/Open Hydrazones. 1. 1D and 2D Variable Temperature NMR Study

1997

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The stereochemistry and conformational behavior of a series of 22 2-methyl-2-alkyl(phenyl, aryl)-4-N-methyl-1,2,3,4-tetrahydro-5H-1,3,4-benzotriazepin-5-ones and their open-chain hydrazone tautomers in various solvents were studied by 1D and 2D NMR techniques in the temperature range from 193 K to 410 K. Molecular rearrangements involving interconversions of the ring and open-chain forms (the latter via amide bond and Z/E CN double bond isomerization), pseudorotation of the ring forms, and N-inversion processes with different rates on the NMR time scale took place, leading to the observation of average and deceptively simple 1H and 13C NMR spectra for most of them at room temperature.

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Section: Resultssupporting

confidence: 77%