Isomericcis-cyclohexano-13-crown-4 ethers: a low-temperature1H and13C NMR investigation
摘要:
The two positionally isomeric cydohexanotetraoxacyclotridecanes (13-crown-4 ethers) were synthesized and studied via low-temperature NMR methods. For the 1,4,8,11-tetraoxa isomer, the cyclohexane ring inversion is a degenerate process, whereas for the 1,4,7,11-tetraoxa isomer, a preference of 1.4 kJ mol(-1) for the form in which the propyleneoxy group is equatorial was determined. Molecular mechanics calculations using MM+ indicated a preference of 0.6 kJ mol(-1) for this conformer. Resonance assignment was facilitated by the synthesis of a selectively deuterated derivative and by COSY, HMQC and HMBC experiments. The results were compared with those for the related 10-crown-3 system and C-13 chemical shift trends are discussed in terms of MM+ calculated geometries. (C) John Wiley & Sons Ltd.
Preparation de derives de composes crown-4 a cycles de 13 a 16 membres, en vue d'obtenir des ionophores selectifs du lithium. Les mesures potentiometriques montrent que c'est les composes 14-crown-4 et 15-crown-4 qui possedent les meilleurs proprietes
准备 de 派生 de composes Crown-4 a cycle de 13 a 16 membres, en vue d'obtenir des ionophores selectifs du 锂。Les mesures potentiometriques montrent que c'est les composes 14-crown-4 et 15-crown-4 qui possedent les meilleurs proprietes
Czech, Bronislaw P.; Zazulak, Wolodymyr; Kumar, Anand, Journal of Heterocyclic Chemistry, 1991, vol. 28, # 5, p. 1387 - 1394
作者:Czech, Bronislaw P.、Zazulak, Wolodymyr、Kumar, Anand、Dalley, N. Kent、Weiming, Jiang、Bartsch, Richard A.
DOI:——
日期:——
KITAZAWA, SADAYA;KIMURA, KEIICHI;YANO, HIDEKI;SHONO, TOSHIYUKI, J. AMER. CHEM. SOC., 1984, 106, N 23, 6978-6983