External oxidant-free electrooxidative intramolecular S-N bond formation for one-pot synthesis for 3,5-disubstituted 1,2,4-thiadiazoles
作者:Qihao Zhong、Shouri Sheng、Junmin Chen
DOI:10.1080/10426507.2020.1768093
日期:2020.12.1
amidines or guanidines to give the corresponding imidoyl thioureas, which are further cyclized in situ via electrooxidativeintramolecular S-N bondformation to promote the final products. This protocol features a metal- and external oxidant-free approach, broad substrate scope, good functional group tolerance, excellent yields, and one-pot operation/reaction without the isolation of the intermediates
摘要 已在未分离的电解条件下开发了用于合成 5-氨基和 3,5-二氨基取代的 1,2,4-噻二唑衍生物的电化学氧化反应方案。新开发的一锅法涉及异硫氰酸酯与脒或胍反应生成相应的亚氨基硫脲,通过电氧化分子内 SN 键的形成进一步原位环化以促进最终产物。该协议具有无金属和无外部氧化剂的方法、广泛的底物范围、良好的官能团耐受性、优异的产量和一锅操作/反应,无需隔离中间体。图形概要
Transition-metal-free S–N bond formation: synthesis of 5-amino-1,2,4-thiadiazoles from isothiocyanates and amidines
has been developed by the reaction of isothiocyanates with amidines. This protocol which is free of metal, catalyst and iodine involves O2 oxidative S–N bond formation for the synthesis of various 5-amino-1,2,4-thiadiazole derivatives with excellent to good yields. High regioselectivity, mild reaction conditions, broad substrate scope and good functional group tolerance are the highlights of the report