A Scalable and Expedient Route to 1-Aza[6]helicene Derivatives and Its Subsequent Application to a Chiral-Relay Asymmetric Strategy
摘要:
A rapid route to diversely functionalized 1-aza[6]helicenes has been achieved via the development of a copper-mediated cross-coupling reaction, followed by PtCl4-catalyzed cycloisomerization. Not only does this method allow access to these functionally important molecules on gram scale, but this strategy Is also suitable for relaying the axial chirality of a key intermediate to the helicity of the product.
通过使用碘基苯作为无毒的碘(III)基氧化剂和碘化铵作为廉价的碘原子源,开发了一种用于亲电子碘化苯酚的氧化方法。通过用K 3 PO 4缓冲反应介质来实现完全受控的单碘化。在温和的温度下,在开放的烧瓶中,该方案以较短的反应时间进行,并且通常收率很高。用富电子和贫电子的酚以及杂环探索了革兰氏反应以及该方案的范围。量子化学计算显示,PhII(OH)·NH 3是最可能的碘化活性物质,呈反应性“ I +synthon。鉴于碘代芳烃部分的相关性,我们在本文中提出了实用,有效和简单的方法,其具有允许进入碘代芳烃核心单元的宽泛的官能团范围。
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。
Practical, mild and efficient electrophilic bromination of phenols by a new I(<scp>iii</scp>)-based reagent: the PIDA–AlBr<sub>3</sub>system
作者:Yuvraj Satkar、Velayudham Ramadoss、Pradip D. Nahide、Ernesto García-Medina、Kevin A. Juárez-Ornelas、Angel J. Alonso-Castro、Ruben Chávez-Rivera、J. Oscar C. Jiménez-Halla、César R. Solorio-Alvarado
DOI:10.1039/c8ra02982b
日期:——
Its stability at 4 °C after preparation was confirmed over a period of one month and no significant loss of its reactivity was observed. Additionally, the gram-scale bromination of 2-naphthol proceeds with excellent yields. Even for stericallyhindered substrates, a moderately good reactivity is observed.
Palladium-catalyzed alkene-directed cross-coupling of aryliodide with another aryl halide through C-H arylation opens a unique avenue for unsymmetrical biaryl-derived molecules. However, homo-coupling of aryliodides often erodes the overall synthetic efficiency. Reported herein is a highly chemoselective Pd0 -catalyzed alkyne-directed cross-coupling of aryliodides with bromophenols, which was subsequently
A highly regioselective Ru(II)-catalyzed [3+2] spiroannulation of 1-aryl-2-naphthols with internal alkynes was developed by using a novel double directing group strategy. This method was compatible with many functional groups, thus affording a variety of sterically congested spirocyclic molecules in high yields.
was developed by using a C(sp3)−H activation/naphthol dearomatization approach. This bimolecular domino reaction of two aryl halides was realized through a sequence of cyclometallation‐facilitated C(sp3)−H activation, biaryl cross‐coupling, and naphthol dearomatization, thus rendering the rapidassembly of a new class of spirocyclic molecules in good yields with broad functional‐group tolerance. Preliminary