Richter cyclization and co-cyclization reactions of triazene-masked diazonium ions
作者:Annelies Goeminne、Peter J. Scammells、Shane M. Devine、Bernard L. Flynn
DOI:10.1016/j.tetlet.2010.10.122
日期:2010.12
(aq) (X = Br or Cl) and NaNO2, followed by spontaneous ring closure to give a mixture of 4-halocinnoline and 4-cinnolinone products. The different products result from competing attack of X− and H2O, respectively, upon an intermediate 2-alkynylphenyl diazonium ion during the cyclization step. In order to improve the chemoselectivity of this reaction, we have utilized triazenes as masked diazonium ions
常规的Richter环化涉及将2-炔基苯胺与HX(aq)(X = Br或Cl)和NaNO 2重氮化,然后自发闭环,得到4-卤代辛啉和4-cinnolinone产物的混合物。不同的产品来自竞争X的攻击导致-和H 2中的环化步骤分别O,中,在中间-2-炔基苯基重氮离子。为了提高该反应的化学选择性,我们利用三氮烯作为掩蔽的重氮离子。这些可以使用MeSO 3进行屏蔽在无水溶剂中的氢和所得的2-炔基苯基重氮鎓离子通过掺入专门添加的亲核试剂进行化学选择性环化。此过程已扩展到拴系的亲核试剂,导致Richter诱导的共环化过程产生环稠合的cinnolines。