Visible Light-Mediated Coupling of Thioureas and 1,3-Dicarbonyls: Towards a Leaving Group-Free Synthesis of Aminothiazoles
作者:Irwan Iskandar Roslan、Kian-Hong Ng、Mohammed Ashraf Gondal、Chanbasha Basheer、Mohamed A. Dastageer、Stephan Jaenicke、Gaik-Khuan Chuah
DOI:10.1002/adsc.201701565
日期:2018.4.17
A synthesis of aminothiazoles from various 1,3‐dicarbonyls and thioureas without a leavinggroup has been developed. The reaction is photocatalyzed by tetraiodofluorescein, an organic dye. Under irradiation with green LEDs, a sulfur radical is generated in situ from thiourea, followed by addition to the enol tautomer, forming the aminothiazole backbone. This novel strategy provides a greener alternative
2-aminothiazoles has been achieved by the reaction of activemethylene ketones with thioureas assisted by ᴅʟ-alanine using NH4I as a redox mediator. The electrochemical protocol proceeds in an undivided cell equipped with graphite plate electrodes under constant current conditions. Various activemethylene ketones, including β-keto ester, β-keto amide, β-keto nitrile, β-keto sulfone and 1,3-diketones, can
2-氨基噻唑的电化学制备是通过活性亚甲基酮与硫脲的反应实现的,该反应由 ᴅʟ-丙氨酸辅助,使用 NH 4 I 作为氧化还原介质。电化学协议在恒定电流条件下在配备石墨板电极的未分割电池中进行。各种活性亚甲基酮,包括β-酮酯、β-酮酰胺、β-酮腈、β-酮砜和1,3-二酮,可以转化为相应的2-氨基噻唑。从机理上讲,原位产生的α-碘酮被认为是关键的活性物质。