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。
A simple Hückel model-driven strategy to overcome electronic barriers to retro-Brook silylation relevant to aryne and bisaryne precursor synthesis
作者:Edward A. Neal、A. Yannic R. Werling、Christopher R. Jones
DOI:10.1039/d0cc08283j
日期:——
ortho-Silylaryl triflate precursors (oSATs) have been responsible for many recent advances in arynechemistry and are most commonly accessed from the corresponding 2-bromophenol. A retro-Brook O- to C-silyl transfer is a key step in this synthesis but not all aromatic species are amenable to the transformation, with no functionalized bisbenzyne oSATs reported. Simple Hückel models are presented which
Stable 2-(trimethylsilyl)phenyl trimethylsilyl ethers, readily obtained from the corresponding halogenated phenols in two steps, were identified as novel benzyne precursors. These species were converted to benzynes by a domino reaction of O-desilylation, O-nonaflylation, and β-elimination under mild conditions using nonafluorobutanesulfonyl fluoride (NfF) and tetrabutylammonium triphenyldifluorosilicate
o-Trialkylsilylaryl triflates, which are useful aryne precursors, are prepared from o-bromophenols by an efficient, one-pot procedure involving O-silylation, metal-halogen exchange, O- to C-silyl migration, and entrapment of the phenoxide with triflic anhydride.