Selective synthesis of novel cyclic phenylazomethine trimers
Selective synthesis of novel cyclic phenylazomethine trimers
复制标题
新型环状苯基偶氮甲碱三聚体的选择性合成
DOI：
10.1021/jo000509c
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发表时间：
2000
影响因子：
3.6
通讯作者：
Yamamoto
中科院分区：
文献类型：
--
作者：
Higuchi;Kimoto;Shiki;Yamamoto
在TiCl(4)或对甲苯磺酸(PTS)存在下，4-氨基二苯甲酮衍生物一步脱水合成了新型环状苯偶氮亚甲基三聚体(CPAs)。在非稀释条件下，以90%以上的产率分离了CPA。以TiCl(4)为脱水剂时，底物α-位大量取代基的诱导提高了CPA的产率。另一方面，PTS是合成苯基CPA的有效催化剂。TiCl(4)和PTS之间的这种不同的反应活性取决于脱水机理是由动力学过程还是热力学过程主导的。核磁共振、UV-Vis光谱和MM2计算表明，与直链低聚苯基偶氮亚胺(OPAS)和苯胺封端的OPAS(OPA‘s)相比，所合成的CPA只具有Z构象和非共轭结构。
Novel cyclic phenylazomethine trimers (CPAs) were synthesized in a one-step dehydration of the 4-aminobenzophenone derivatives in the presence of TiCl(4) or p-toluenesulfonic acid (PTS). The CPAs were isolated in over 90% yield under nondilute conditions. When using TiCl(4) as the dehydration agent, the induction of bulky substituents at the alpha-position of the substrate enhanced the yields of the CPAs. On the other hand, PTS served as an effective catalyst for the synthesis of the phenyl-substituted CPA. This different reactivity between TiCl(4) and PTS depends on the dehydration mechanism being dominated by a kinetic process or thermodynamic one. The obtained CPAs were confirmed by NMR, UV-vis spectra, and MM2 calculation to have only a Z conformation and a nonconjugated structure compared to the linear oligophenylazomethines (OPAs) and the aniline-capped OPAs (OPA's).