1-二甲氨基萘-8-酮的O - vs. N-质子化:形成一个周边的N–C键或一个氢键,形成羰基的π电子密度†
摘要:
X射线晶体学和固态NMR测量表明,一系列1-二甲基氨基萘8-酮的质子化导致O质子化,在周边基团之间形成长的N–C键(1.637–1.669Å),或者N质子化并在羰基的π表面形成氢键,后者出现在较大的酮基(C(O)R,R =叔丁基和苯基)上。固态15N MAS NMR研究清楚地区分了这两个系列,前者产生的屏蔽效应明显更多。通过相关化学位移参数的DFT计算可以准确地证实这一点。在母体酮中,X射线晶体学分析表明,在所有情况下,氮孤对都指向羰基。
Synthesis of 8-substituted 1-naphthylamine derivatives. exceptional reactivity of the substituents.
作者:Anthony J. Kirby、Jonathan M. Percy
DOI:10.1016/s0040-4020(01)86220-7
日期:1988.1
N- vs O-Protonation and the Transannular Substituent Interaction in 8-(Dimethylamino)-1-acetonaphthone
作者:Ingeborg I. Schuster、Alan J. Freyer、Arnold L. Rheingold
DOI:10.1021/jo000615e
日期:2000.9.1
Dynamic NMR measurements of 8-(dimethylamino)-1-acetonaphthone 1 in neutral solutions reveal a solvent dependency of the barrier to NMe group interchange similar to that reported for N,N-dimethylacetamide. Titrating 1 with TFA in solvents of varying donicities gives rise to equilibrium mixtures of N-protonated aminoketone 2 and the O-protonated transannular addition product 3, the interconversion rate of which is slow on the NMR time scale at ambient temperature. The preference for O- or N-protonation is medium-dependent, the amount of N-protonated 2 increasing with a decrease in the nucleophilicity of the solvent. The set of equilibria which govern the interconversion of 2 and 3 in the titration mixtures are identified and their equilibrium constants evaluated from the NMR data. X-ray analysis of the crystalline trifluoroacetate salt of O-protonated 3 indicates that the transannular N ... CO bond of 3 is formed to an extent of only 80%. The equilibrium distribution of 2 and 3, paired with the tetrafluoroborate anion, depends on both the nucleophilicity and the polarity of the solvent. In PhNO2 the enthalpy change 3 --> 2 amounts to 2.6 kcal/mol.
KIRBY, ANTHONY J.;PERCY, JONATHAN M., TETRAHEDRON, 44,(1988) N 22, C. 6903-6910