通过使用曙红 Y 作为光催化剂和可回收离子液体作为溶剂,开发了一种无金属和氧化剂的光氧化还原催化 2 H-吲唑三氟甲基化的方案。在该协议中,在温和条件下,以中等到良好的收率获得了一系列三氟甲基化产品。该反应通过自由基机制进行,具有广泛的底物范围、优异的区域选择性和良好的官能团耐受性。此外,该协议的实用性通过雌激素受体β(ERβ)和药物格拉司琼的高选择性配体的合成得到证明。该协议为三氟甲基化反应提供了一种温和且环保的解决方案。
Selective Synthesis of Indazolo[2,3‐
<i>a</i>
]quinolines via Rh(III)‐Catalyzed Oxidant‐Free [4+2] or [5+1] Annulation of 2‐Aryl‐2
<i>H</i>
‐indazoles with
<i>α</i>
‐Diazo Carbonyl Compounds
作者:Shenghai Guo、Lincong Sun、Xuzhuo Li、Xinying Zhang、Xuesen Fan
DOI:10.1002/adsc.201901422
日期:2020.2.21
A selective synthesis of 5,6‐disubstituted and 5‐substituted indazolo[2,3‐a]quinolines through a Rh(III)‐catalyzed oxidant‐free annulation of 2‐aryl‐2H‐indazoles with α‐diazo carbonyl compounds is reported. With 2‐aryl‐2H‐indazoles as the substrates, α‐diazo carbonyl compounds could act as a C2 synthon to afford 5,6‐disubstituted indazolo[2,3‐a]quinolines via a Rh(III)‐catalyzed [4+2] annulation. On
通过Rh(III)催化的2-芳基-2 H-吲唑与α-重氮羰基化合物的无氧化剂环氧化反应选择性合成5,6-二取代和5-取代的吲唑并[2,3- a ]喹啉是报告。以2-芳基-2 H-吲唑为底物,α-重氮羰基化合物可作为C2合成子,通过Rh(III)催化[ 5,6-二取代的吲唑并[2,3- a ]喹啉] [4 +2]。另一方面,当使用2-芳基-3-甲酰基-2 H-吲唑类作为底物时,α-重氮羰基化合物转变为C1合成子,需要经历更复杂的[5 + 1]环化工艺来提供5位取代的吲哚并[2,3- a ]喹啉。
Regioselective Synthesis of 2<i>H</i>-Indazoles Using a Mild, One-Pot Condensation–Cadogan Reductive Cyclization
作者:Nathan E. Genung、Liuqing Wei、Gary E. Aspnes
DOI:10.1021/ol5012423
日期:2014.6.6
An operationally simple and efficient one-pot synthesis of 2H-indazoles from commercially available reagents is reported. Ortho-imino-nitrobenzene substrates, generated via condensation, undergo reductive cyclization promoted by tri-n-butylphosophine to afford substituted 2H-indazoles under mild reaction conditions. A variety of electronically diverse ortho-nitrobenzaldehydes and anilines were examined. To further extend the scope of the transformation, aliphatic amines were also employed to form N2-alkyl indazoles selectively under the optimized reaction conditions.