Synthesis of Glycal-Based Chiral Benzimidazoles by VO(acac)2−CeCl3 Combo Catalyst and Their Self-Aggregated Nanostructured Materials
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- 作者：Dilip K. Maiti ; Samiran Halder ; Palash Pandit ; Nirbhik Chatterjee ; Dripta De Joarder ; Nabyendu Pramanik ; Yasmin Saima ; Amarendra Patra ; Prabir K. Maiti
- 刊名：Journal of Organic Chemistry
- 出版年：2009
- 出版时间：November 6, 2009
- 年：2009
- 卷：74
- 期：21
- 页码：8086-8097
- 全文大小：1216K
- 年卷期：v.74,no.21(November 6, 2009)
- ISSN：1520-6904
文摘
VO(acac)2−CeCl3 combo catalyst has been developed for chemoselective cyclocondensation cum oxidation under mild reaction conditions toward synthesis of a new class of optically pure compounds, 2-(2′-C-3′,4′,6′-tri-O-benzyl/methyl-glycal)-1H-benzimidazoles. It involves an operationally simple synthetic protocol efficient for the syntheses of a wide range of chiral benzimidazoles in high yields without formation of undesired 1,2-disubstituted and pseudoglycal byproducts. Vanadium(V) is found as active oxidant for the chemical processes which is investigated by UV absorption spectroscopy. Highly ordered one-dimensional low molecular mass organic nanostructured materials are fabricated by nanocrystallization of the chiral nanoscale building blocks. Theoretical calculation by the B3LYP/6-31G** level of theory of the glycal-based chiral benzimidazoles shows out of planar geometry of the 1H-anthra[1,2-d]imidazole-6,11-dione moiety, which is responsible for the strong self-aggregation to generate ultralong nanostructured materials. We have also found nice agreement between the theoretical results with the experimental observation in 2D-NOESY experiments. The photophysical property of the solid nanostructured materials is also reported.