Synthesis, structure and stability of E/Z-isomers of novel conjugated enamines prepared from 9-arylmethyl- or 9-arylpropenyl-9H-carbazole with arylmethyleneanilines
作者:Martino Paventi、Allan S. Hay
DOI:10.1039/a604969i
日期:——
Active methylene groups, substituted by
9H-carbazol-9-yl (Carb) and aryl or 2-phenylethenyl
groups, condense with arylmethyleneanilines in DMF at 75 °C
in the presence of ButOK to form the
corresponding enamines [(Carb)(Ar1)C=C(Ar2)H] and
dienamines
[(Ar3)HCC(Carb)CHCHPh] in
almost quantitative yield. The 1H and 13C NMR
spectra for the enamine 1′Z-isomers [16
(Ar1 = Ar2 =
4-fluorophenyl), 17 (Ar1 = 4-fluorophenyl,
Ar2 = 4-tert-butoxyphenyl),
19
(Ar1 = Ar2 = 4-
tert-butoxyphenyl)], dienamine
1′Z-isomers [14a
(Ar3 = 1-naphthyl), 14b
(Ar3 = 4-methoxyphenyl), 14c
(Ar3 = Ph)] and
1′E-isomers [15a
(Ar3 = 1-naphthyl), 15c
(Ar3 = Ph)] and precursors are assigned with
the aid of COSY, HMBC, and HMQC techniques. The geometrical isomerism of
the different dienamines 14–15 is established by
3JC-H NMR couplings and that of
enamine 12 by a difference NOE experiment. X-Ray crystal structures for
16, 14a and 15c corroborate the isomerism results deduced by NMR
studies. Dienamines 14a and 15a hydrolyse to the ketone under relatively
strong acid conditions [AcOH–HCl–H2O
(18∶1∶1 v/v)] under reflux over 7 h. There is an equilibrium
between 14c and 15c in 1,2,4-trichlorobenzene at
180 ± 1 °C with
K = 15c/14c = 0.77 as
estimated from the kinetic rate profiles from HPLC data acquired over 4
days. However, under the same conditions, 14a and 15a undergo an
equilibration concurrent with a reaction (monitored over 9 days) giving
apparently a carbazolyl-substituted phenylphenanthrene. In contrast,
enamine 16 is thermally stable with no detectable change after boiling
for 4 days in 1,2,4-trichlorobenzene.
活性亚甲基,被取代
9H-咔唑-9-基(Carb)和芳基或2-苯基乙烯基
基团,与芳基亚甲基苯胺在 DMF 中于 75 °C 缩合
在 ButOK 存在的情况下形成
相应的烯胺 [(Carb)(Ar1)C=C(Ar2)H] 和
二烯胺
[(Ar3)HCC(Carb)CHCHPh] 在
几乎定量产率。 1H 和 13C NMR
烯胺 1′Z-异构体的光谱 [16
(Ar1 = Ar2 =
4-氟苯基), 17 (Ar1 = 4-氟苯基,
Ar2=4-叔丁氧基苯基),
19
(Ar1 = Ar2 = 4-
叔丁氧基苯基)],二烯胺
1′Z-异构体[14a
(Ar3 = 1-萘基), 14b
(Ar3 = 4-甲氧基苯基), 14c
(Ar3 = Ph)] 和
1′E-异构体 [15a
(Ar3 = 1-萘基), 15c
(Ar3 = Ph)] 和前体被指定为
借助 COSY、HMBC 和 HMQC 技术。几何异构现象
不同的二烯胺 14-15 是由
3JC-H NMR 联轴器和
烯胺 12 通过差异 NOE 实验得到。 X 射线晶体结构
图16、14a和15c证实了NMR推导的异构结果
研究。二烯胺 14a 和 15a 在相对温度下水解为酮
强酸条件[AcOH–HCl–H2O
(18∶1∶1 v/v)]回流7小时。有一个平衡点
1,2,4-三氯苯中 14℃ 至 15℃
180 ± 1 °C 与
K = 15c/14c = 0.77 作为
根据超过 4 次采集的 HPLC 数据的动力学速率曲线估计
天。然而,在相同条件下,14a和15a经历了
平衡同时发生反应(监测超过 9 天)
显然是咔唑基取代的苯基菲。相比之下,
烯胺 16 具有热稳定性,煮沸后没有可检测到的变化
在 1,2,4-三氯苯中浸泡 4 天。