One-pot synthesis of indeno-1,2-thiazines, -[1,2]dithioles and thiophenes; new liquid crystalline materials
作者:Lidia S. Konstantinova、Oleg A. Rakitin、Charles W. Rees、Ljudmila I. Souvorova、Tomás Torroba
DOI:10.1039/a809808e
日期:——
In a search for further examples of a new type of discotic liquid crystal, we have examined the reactions of S2Cl2 in the presence of a chlorinating agent (NCS) and a base (Hünig’s base or DABCO), mostly in THF, with cyclopent-1-enylacetic acid 6, inden-3-ylacetic acid 8 and its nitrile 16 and 1-(dicyanomethylene)indane 22. The cyclopentene acid 6 gives purple crystals of the trichlorocyclopenta[1,2]dithiole ester 7, the product of heterocyclic ring formation, chlorination and dehydrochlorination and, unexpectedly, conversion of the acid in THF into its 4-chlorobutyl ester. Indenylacetic acid 8 gives methyleneindenes 10 and 11, the tricyclic 1,2-dithiolone 12 and the deep purple thiophene 13. Indenylacetonitrile 16 gives the chlorocyanomethylene indane 17 and the E- and Z- isomers of both the dichloroindene 18 and the monochloroindane 19, depending upon the precise reaction conditions. Dicyanomethylene indane 22 gives the dichloroindene 23 and the red, thermochromic indeno-1,2-thiazine 24; the analogous cyano-ester 25 gives the corresponding products. On melting, crystals of 13 and 23 are strongly birefringent. Mechanisms are proposed for the new transformations.
为了寻找新型盘状液晶的更多实例,我们研究了 S2Cl2 在氯化剂(NCS)和碱(许尼 格碱或 DABCO)存在下(主要在 THF 中)与环戊-1-烯基乙酸 6、茚-3-乙酸 8 及其腈 16 和 1-(二氰基亚甲基)茚 22 的反应。环戊烯酸 6 会产生紫色的三氯环戊二烯并[1,2]二硫代酯 7 结晶,这是杂环形成、氯化和脱氢氯化的产物,而且出乎意料的是,该酸在四氢呋喃中会转化为其 4-氯丁酯。茚乙酸 8 可以生成亚甲基茚 10 和 11、三环 1,2-二硫环戊酮 12 以及深紫色噻吩 13。根据精确的反应条件,茚乙腈 16 可以得到氯氰亚甲基茚 17 以及二氯茚 18 和一氯茚 19 的 E- 和 Z- 异构体。二氰亚甲基茚 22 可以生成二氯茚 23 和红色的热致变色茚-1,2-噻嗪 24;类似的氰酯 25 可以生成相应的产物。熔化时,13 和 23 的晶体具有强烈的双折射。提出了新转化的机理。