kinetics of these hetero Diels−Alderreactions, which have been followed by dilatometry and 1H-NMR spectroscopy, obey second-order rate laws. Since the observed rate constants are only 30−300 times larger than those calculated for the stepwise process by the linear free-enthalpy relationship lg k = s (E + N), it is concluded that these cycloadditions proceed in a stepwise manner or through pericyclic
N,N-二甲基亚甲基铵离子 1 与 1,3-二烯 2a-2f 发生区域和立体选择性反应,生成 1,2,5,6-四氢吡啶鎓离子 3。这些杂 Diels-Alder 反应的动力学具有其次是膨胀法和 1H-NMR 光谱,服从二阶速率定律。由于观察到的速率常数仅比通过线性自由焓关系 lg k = s (E + N) 为逐步过程计算的速率常数大 30-300 倍,因此可以得出结论,这些环加成以逐步方式或通过周环进行两个新 σ 键的协同形成没有显着稳定的过渡态。相比之下,亚胺离子 1 与环戊二烯 (2g) 的反应产生 2,2-二甲基-2-azoniabicyclo[2.2。
Lukes; Pliml, Collection of Czechoslovak Chemical Communications, 1950, vol. 15, p. 512,513
作者:Lukes、Pliml
DOI:——
日期:——
Lukes; Pliml, Collection of Czechoslovak Chemical Communications, 1950, vol. 15, p. 463,465
作者:Lukes、Pliml
DOI:——
日期:——
LAIRD T.; OLLIS W. D.; SUTHERLAND I. D., J. CHEM. SOC. PERKIN TRANS., 1980, PART 1, NO 9, 2033-2048
作者:LAIRD T.、 OLLIS W. D.、 SUTHERLAND I. D.
DOI:——
日期:——
Base catalysed rearrangements involving ylide intermediates. Part 7. The rearrangements of allyl(pentadienyl)- and propynyl(pentadienyl)ammonium cations. The [5,4] sigmatropic rearrangement
作者:Trevor Laird、W. David Ollis、Ian O. Sutherland
DOI:10.1039/p19800002033
日期:——
The basecatalysedrearrangements of the cations (7), (17), (22), and (27) gave the enamines (9), (18), (23), and (28), which on hydrolysis yielded the aldehydes (10), (19), (24), and (29) respectively. The reactions are shown to be concerted [5,4] sigmatropic rearrangements proceeding via a nine-membered transition state involving 10π electrons. The basecatalysedrearrangements of the 3-phenylprop-2-ynyl