A novel [4+1] spiroannulation of o‐ & p‐bromophenols with α,β‐unsaturated imines has been developed for the direct synthesis of a new family of azaspirocyclic molecules. Notably, several other halophenols (X=Cl, I) were also applicable for this transformation. Moreover, a catalytic asymmetric version of the reaction was realized with 1‐bromo‐2‐naphthols by using a chiral ScIII/Py‐Box catalyst. Mechanistic
已经开发了一种新颖的[4 + 1]邻和对溴苯酚与α,β-不饱和亚胺螺环合成的方法,用于直接合成新的氮杂螺环分子家族。值得注意的是,其他几种卤代酚(X = Cl,I)也适用于该转化。此外,通过使用手性Sc III / Py-Box催化剂,使用1-溴-2-萘酚实现了反应的催化不对称形式。机理研究表明,该多米诺反应是通过苯酚衍生物在其卤代位置的亲电触发的脱芳香化作用进行的,然后通过基于自由基的S RN 1机理用N-亲核试剂进行卤素置换。
Lewis Acid‐Mediated Cyanation of Phenols Using
<i>N</i>
‐Cyano‐
<i>N</i>
‐phenyl‐
<i>p‐</i>
toluenesulfonamide
作者:Wu Zhang、Tao Li、Qingli Wang、Wanxiang Zhao
DOI:10.1002/adsc.201900813
日期:2019.11.5
Lewisacid‐mediated cyanation of phenol derivatives with N‐cyano‐N‐phenyl‐p‐toluenesulfonamide (NCTS) has been developed. The reaction proceeded efficiently with high regioselectivity to produce aromatic nitriles in moderate to excellent yields, which provides a direct and practical access to valuable products.
Ni‐catalyzed decarboxylative cross‐coupling of potassium polyfluorobenzoates with unactivated phenol and phenylmethanol derivatives is described. This novel transformation provides a practical and efficient protocol towards the synthesis of important polyfluorobiaryls and polyfluorinated diarylmethanes, and greatly enlarges the range of electrophiles utilized in decarboxylative coupling. Remarkably, preliminary
The iron-catalyzed construction of Csp2–Si bonds via unreactive C–O bonds possesses a challenging topic in organic chemistry. Herein we report an iron-catalyzed silylation of aryl and alkenylcarbamates via C–O bond activation. This protocol features high efficiency and a broad substrate scope, enabling the late-stage silylation of biorelevant compounds and thus providing a good method to access valuable
A chemo- and regioselective Pd(0)-catalyzed spiroannulation has been successfully developed. The key feature of this method is the use of readily available 1,2-dihaloarenes, alkynes and 2-naphthols for the rapid assembly of spirocarbocyclic molecules. Mechanistic studies revealed that this domino reaction proceeded through a cascade of oxidative addition to Pd(0), alkyne migratory insertion, and 2