Journal of the American Chemical Society p. 12567 - 12577 (1995)
Update date:2022-08-28
Topics:
Brown, Jay H.
Bushweller, C. Hackett
2-(Diethylamino)propane (DEAP) and 2-(dibenzylamino)propane (DBAP) possess similar molecular symmetries. Interconversion among the stable equilibrium conformations occurs by inversion-rotation at the pyramidal nitrogen and by isolated rotation about carbon-nitrogen bonds. In DEAP and DBAP, the fact that stable equilibrium conformations cannot have destabilizing syn-1,5 interactions between methyl or phenyl groups limits the number of equilibrium conformations that will be present at concentrations high enough to be NMR detectable. The 1H and 13C{1H} NMR spectra of DEAP at 100 K show two diastereomeric pairs of enantiomeric conformations. One pair of enantiomers has the isopropyl methine proton and both ethyl methyl groups gauche to the lone pair (75%). The other pair has the methine proton anti to the lone pair with the ethyl methyl groups respectively gauche and anti to the lone pair (25%). The barrier to inversion-rotation in DEAP (ΔG? = 6.4 kcal/mol) is higher than barriers to isolated rotation about carbon-nitrogen bonds (ΔG? = 5.3-5.7 kcal/mol). The 1H and 13C{1H} NMR spectra of DBAP at 100 K show just one pair of enantiomeric conformations that have the isopropyl methine proton and both phenyl groups gauche to the lone pair. There is no evidence in the NMR spectrum at 100 K for those conformations of DBAP that have a phenyl group anti to the lone pair. The barrier to inversion-rotation in DBAP (ΔG? = 6.4 kcal/mol) is higher than the barrier to racemization via isolated rotation about carbon-nitrogen bonds (ΔG? = 5.5 kcal/mol). Molecular mechanics calculations of conformational energies are in good agreement with the observed conformational preferences.
View MoreNeworld Chemical Co., Ltd Shanghai
Contact:+86-21-62202658
Address:11F, Blvd 2, No. 1969 PuXing Rd, Shanghai
Shanghai Haoyuan Chemexpress Co., Ltd.
Contact:86-21-51870955;58998985;58999585
Address:Room 601, No. 2 BLD, NO. 720, Cailun Road, Zhangjiang, Shanghai, China
A.M FOOD CHEMICAL CO., LIMITED
Contact:86-531-87100375
Address:20Floor,Bblock,1Building,pharma-valley,Jinan,China
Contact:+86-025-52406782
Address:8 Taizishan Rd., Yanjiang Industrial Development Area, Nanjing, Jiangsu, China.
Contact:13813902930 025-52714267
Address:20 Fengji Road, Yuhua Economic Development Zone, Nanjing, Jiangsu, P. R. China
Doi:10.1016/S0040-4039(01)85975-X
(1979)Doi:10.1246/bcsj.20110043
(2011)Doi:10.1021/jo502885v
(2015)Doi:10.1016/j.tetlet.2010.10.034
(2010)Doi:10.1002/bkcs.11450
(2018)Doi:10.1134/S0965544115080186
(2016)