Chameleonic Reactivity of Vicinal Diazonium Salt of Acetylenyl-9,10-anthraquinones: Synthetic Application toward Two Heterocyclic Targets
作者:A. A. Stepanov、L. M. Gornostaev、S. F. Vasilevsky、E. V. Arnold、V. I. Mamatyuk、D. S. Fadeev、B. Gold、I. V. Alabugin
DOI:10.1021/jo2014214
日期:2011.11.4
the aryl alkyne moiety and an OAc substituent at C4. The latter process provides a new synthetic route to 3-ethynyl-[1,9-cd]isoxazol-6-ones that are difficult to access otherwise. DFT calculations suggest that donor substituents have only a minor effect on alkyne and diazonium polarization in the reactant but provide specific transition state stabilization by stabilizing the incipient vinyl cation.
1-氨基-2-乙炔基-9,10-蒽醌重氮化中产物的性质强烈取决于炔烃和蒽醌核上取代基的性质。第四位的供体取代(NHAr,OH)使C1处的重氮盐稳定,从而减慢了C2处的芳基乙炔基取代基的亲电子环化作用。该作用允许用叠氮化物基团取代重氮鎓,并随后在保留炔的情况下封闭成异恶唑环。相反,对于芳基炔基部分的供体取代基和C4处的OAc取代基,可以观察到亲电的5- exo - dig环化反应生成稠合的吡唑。后一种工艺为3-乙炔基-[1,9- cd]的合成提供了一条新途径。] isoxazol-6-否则很难获得的化合物。DFT计算表明,供体取代基对反应物中炔烃和重氮鎓的极化影响较小,但通过稳定初始乙烯基阳离子可提供特定的过渡态稳定度。该分析提供了有关亲电5- exo - dig的第一批计算数据以其亲本形式和亲核试剂促进的形式进行环化。该环化反应是一个相对较快但吸热的过程,通过在五元杂芳族环中进行烯醇-酮互