Abstract
1,2,4,5-Tetrazines (prepared from aryl nitriles) condense with isoxazolylcyclobutanones (prepared from 3-benzenesulfonyl-3-vinylcyclobutanol) in methanolic KOH to give conformationally restricted 6-isoxazol-5-yl-6,7- dihydro-5H-[1,2]diazocin-4-ones. The solution 1H NMR spectra of dihydrodiazocinone 1a with phenyl moieties at C3 and C8 reveal two conformations of the eight-membered heterocycle that are non-interconverting on the NMR time scale at ambient temperature. The kinetics of the conversion process, followed by 1H NMR between 21 and 70 °C in DMSO solution, yield an activation energy of ∼21 kcal/mol relative to the kinetic conformer and show an equilibrated ratio of ∼5:1 of the thermodynamic to the kinetic conformers. The electronic structure calculations on a model dihydrodiazocinone predict geometries for the two conformations. One of these geometries agrees with the X-ray crystallographic analysis of the thermodynamic conformation of 1a.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2480-2485 |
| Number of pages | 6 |
| Journal | Journal of Organic Chemistry |
| Volume | 71 |
| Issue number | 6 |
| DOIs | |
| State | Published - Mar 17 2006 |
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ASJC Scopus subject areas
- Organic Chemistry
Cite this
Diazocinones : Synthesis and conformational analysis. / Robins, Lori I.; Carpenter, Richard D.; Fettinger, James C.; Haddadin, Makhluf J.; Tinti, Dino S.; Kurth, Mark J.
In: Journal of Organic Chemistry, Vol. 71, No. 6, 17.03.2006, p. 2480-2485.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Diazocinones
T2 - Synthesis and conformational analysis
AU - Robins, Lori I.
AU - Carpenter, Richard D.
AU - Fettinger, James C.
AU - Haddadin, Makhluf J.
AU - Tinti, Dino S.
AU - Kurth, Mark J.
PY - 2006/3/17
Y1 - 2006/3/17
N2 - 1,2,4,5-Tetrazines (prepared from aryl nitriles) condense with isoxazolylcyclobutanones (prepared from 3-benzenesulfonyl-3-vinylcyclobutanol) in methanolic KOH to give conformationally restricted 6-isoxazol-5-yl-6,7- dihydro-5H-[1,2]diazocin-4-ones. The solution 1H NMR spectra of dihydrodiazocinone 1a with phenyl moieties at C3 and C8 reveal two conformations of the eight-membered heterocycle that are non-interconverting on the NMR time scale at ambient temperature. The kinetics of the conversion process, followed by 1H NMR between 21 and 70 °C in DMSO solution, yield an activation energy of ∼21 kcal/mol relative to the kinetic conformer and show an equilibrated ratio of ∼5:1 of the thermodynamic to the kinetic conformers. The electronic structure calculations on a model dihydrodiazocinone predict geometries for the two conformations. One of these geometries agrees with the X-ray crystallographic analysis of the thermodynamic conformation of 1a.
AB - 1,2,4,5-Tetrazines (prepared from aryl nitriles) condense with isoxazolylcyclobutanones (prepared from 3-benzenesulfonyl-3-vinylcyclobutanol) in methanolic KOH to give conformationally restricted 6-isoxazol-5-yl-6,7- dihydro-5H-[1,2]diazocin-4-ones. The solution 1H NMR spectra of dihydrodiazocinone 1a with phenyl moieties at C3 and C8 reveal two conformations of the eight-membered heterocycle that are non-interconverting on the NMR time scale at ambient temperature. The kinetics of the conversion process, followed by 1H NMR between 21 and 70 °C in DMSO solution, yield an activation energy of ∼21 kcal/mol relative to the kinetic conformer and show an equilibrated ratio of ∼5:1 of the thermodynamic to the kinetic conformers. The electronic structure calculations on a model dihydrodiazocinone predict geometries for the two conformations. One of these geometries agrees with the X-ray crystallographic analysis of the thermodynamic conformation of 1a.
UR - http://www.scopus.com/inward/record.url?scp=33645031061&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33645031061&partnerID=8YFLogxK
U2 - 10.1021/jo052577a
DO - 10.1021/jo052577a
M3 - Article
C2 - 16526800
AN - SCOPUS:33645031061
VL - 71
SP - 2480
EP - 2485
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 6
ER -