Synthesis of Annulated Arenes and Heteroarenes Involving Lewis Acid-Mediated Regioselective Annulation of Unsymmetrical 1,2-(Diaryl/diheteroarylmethine)dipivalates
作者:Ramakrishnan Sivasakthikumaran、Meganathan Nandakumar、Arasambattu K. Mohanakrishnan
DOI:10.1021/jo301410w
日期:2012.10.19
A ZnBr2-mediated regioselectiveannulation of unsymmetrical 1,2-diarylmethinedipivalates in DCM at room temperature led to the formation of annulated arenes and heteroarenes. The annulation of the dipivalate proceeds through the intermediacy of benzylic carbocations followed by intramolecular cyclization and subsequent aromatization to give the annulated products. The annulation methodology is highly
室温下,DCM中ZnBr 2介导的不对称1,2-二芳基次甲基新戊二酸酯的区域选择性环化导致环化的芳烃和杂芳烃的形成。二戊酸酯的环化通过苄基碳阳离子的中间进行,然后进行分子内环化和随后的芳构化,以得到环化的产物。对于蒽和萘并[ b ]噻吩类似物的合成,环空方法学是非常有效的。
Regioselective Annulation of Unsymmetrical 1,2-Phenylenebis(diaryl/diheteroarylmethanol): A Facile Synthesis of Anthracene, Tetracene, and Naphtho[<i>b</i>]thiophene Analogues
作者:Ramakrishnan Sivasakthikumaran、Settu Muhammad Rafiq、Elumalai Sankar、J. Arul Clement、Arasambattu K. Mohanakrishnan
DOI:10.1002/ejoc.201501087
日期:2015.12
A systematic study on the regioselective cyclization of benzene- and naphthalene-based unsymmetrical diols with HBr (33 %) in acetic acid at room temperature led to the formation of annulation products. By using this method, synthesis of a wide variety of anthracene, tetracene and naphtho[b]thiopheneanalogues was achieved in good to excellent yields. By employing HBr (33 %) in acetic acid as a catalyst
Lewis Acid/Brönsted Acid Mediated Benz-Annulation of Thiophenes and Electron-Rich Arenes
作者:Settu Muhamad Rafiq、Ramakrishnan Sivasakthikumaran、Arasambattu K Mohanakrishnan
DOI:10.1021/ol501006t
日期:2014.5.16
A facile preparation of benz-annulated heterocycles were achieved at rt involving a Lewis acid/Brönstedacidmediated annulation of heterocycles using 2,5-dimethoxytetrahydrofuran as a four-carbon synthon. The benz-/naphth-annulation was found to be successful with electron-rich arenes as well.