Synthesis of some novel imidate derivatives of thiophene and furan: Investigations of their metallation properties and some synthetic applications
作者:Richard A. Barcock、Derek J. Chadwick、Richard C. Storr、Lance S. Fuller、John H. Young
DOI:10.1016/s0040-4020(01)86710-7
日期:1994.4
solvents, and reaction conditions revealed almost exclusive C5-lithiation. This regioselectivity is in contrast to the C3-lithiation reported for the oxazolino functionality (a cyclic imidate). The synthetic utility of the C5-lithiated intermediate of methyl N-methyl-thiophene-2-carboximidate with various electrophiles is demonstrated. C3-Lithiation has been effected in the case of methyl N-methylthi
通过甲醇中的甲醇钠与相应的N-甲基和N的反应,以优异的收率合成了噻吩和呋喃的N-甲基-甲基和N-(2,4,6-三甲基)苯基-2-甲基亚甲基苯甲酸酯-(2,4,6-三甲基)苯基-2-羧酰亚胺基氯,依次通过在纯亚硫酰氯中回流而从它们各自的仲酰胺中获得。对这些杂芳基-2-亚氨酸盐与各种锂化剂,溶剂和反应条件的定向锂化性能进行了彻底的研究,结果表明几乎没有C5锂化。该区域选择性与恶唑啉基官能团(环状亚氨酸酯)报道的C3-锂化相反。证明了N-甲基-噻吩-2-羧甲基丙烯酸甲酯与各种亲电试剂的C5-锂化中间体的合成效用。当C5-位被可移动的三甲基甲硅烷基保护时,对于甲基N-甲基噻吩-2-羧酰亚胺酯,已经进行了C3-锂化。发现N-未取代的亚氨酸甲酯噻吩-2-羧甲基丙烯酸甲酯消除了甲醇离子,并随后进行了C5锂化反应,得到了带有LDA的5-硫代噻吩-2-甲腈。正丁基锂主要是由亲核加成到腈基上而产生的产物。