New pentacyclic ring systems: intramolecular cyclization of o,o′-disubstituted bibenzothiazoles
作者:Livio Racané、Helena Čičak、Zlatko Mihalić、Grace Karminski-Zamola、Vesna Tralić-Kulenović
DOI:10.1016/j.tet.2011.02.037
日期:2011.4
Efficient methods for the preparation of isomeric o,o′-diaminobibenzothiazoles (8a and 11a) and o,o′-diamino-2,2′-dimethylbibenzothiazoles (8b and 11b), potentially valuable building blocks for construction of hitherto unknown dithiazolo annulated pentacyclic heterocycles, have been developed. The dithiazolo annulated benzo[c]cinnolines 9a, 9b, and 12a were prepared from the corresponding diamines
制备异构体邻,邻′ -二氨基联苯并噻唑(8a和11a)和邻类,邻′-二氨基-2,2′-二甲基联苯并噻唑(8b和11b)的有效方法,这可能是迄今为止迄今未知的二噻唑并环化的五环结构的潜在有价值的构建基杂环,已经被开发出来。通过用PhI(OAc)2氧化由相应的二胺制备二噻唑并环氧化的苯并[ c ]喹啉9a,9b和12a。二噻唑并环咔唑13通过在H 3 PO 4中进行热环化反应,由相应的二胺高效制备14和14。的减少和产物形成的不寻常的过程ø,ö '-dinitrosubstituted bibenzothiazoles图6a和6b中与的SnCl 2的酸性条件是通过DFT量子力学计算合理化下。有人提出,环状产物是由二亚硝基衍生物和开壳物种直接在还原路径上形成的。