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。
Electrochemical Radical–Radical Cross-Coupling Approach between Sodium Sulfinates and 2<i>H</i>-Indazoles to 3-Sulfonylated 2<i>H</i>-Indazoles
作者:Wansoo Kim、Hun Young Kim、Kyungsoo Oh
DOI:10.1021/acs.orglett.0c02144
日期:2020.8.21
A direct cross-coupling between sodium sulfinates and 2H-indazoles has been developed under electrochemical conditions. The utilization of a graphite anode and platinum cathode in an undivided cell with a constant current of 7 mA allowed the concurrent oxidations of sulfinates and 2H-indazoles to sulfonyl radical and radical cationic 2H-indazoles, facilitating the direct radical–radical coupling strategy
operationally simple method for the regioselective synthesis of 2-aryl-substituted 2H-indazoles is reported. The Pd-catalyzed reaction between easily available 2-bromobenzyl bromides and arylhydrazines employing Cs2CO3 as the base and t-Bu3PHBF4 as the ligand in DMSO at 120 °C in a sealed tube delivers the 2-substituted-2H-indazoles in a single synthetic step with yields up to 79%. The newmethod is based on
报道了直接和操作简单的方法用于区域选择性合成2-芳基取代的2 H-吲唑。容易获得的2-溴苄基溴化物和芳基肼采用铯之间的Pd-催化反应2 CO 3作为碱和吨-Bu 3 PHBF 4作为在密封管中120℃下在DMSO中配体递送2-取代- 2 ħ -吲唑在单个合成步骤中的收率高达79%。该新方法基于区域选择性的分子间N-苄基化,然后进行分子内N-芳基化和氧化。
Visible-Light-Induced Regioselective Cross-Dehydrogenative Coupling of 2<i>H</i>-Indazoles with Ethers
A visible-light-promoted regioselective C(sp2)–H/C(sp3)–H cross-dehydrogenative coupling between 2H-indazoles and ethers has been achieved using a catalyticamount of rose bengal as an organophotoredox-catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant at ambient temperature underaerobicconditions. A variety of C-3 oxyalkylated 2H-indazoles have been synthesized in moderate to good yields
Synthesis of Fused or Spiro Polyheterocyclic Compounds via the Dehydrogenative Annulation Reactions of 2-Arylindazoles with Maleimides
作者:Chenhao Guo、Bin Li、Huilai Liu、Xiaopeng Zhang、Xinying Zhang、Xuesen Fan
DOI:10.1021/acs.orglett.9b01889
日期:2019.9.20
maleimides for the switchable synthesis of indazolo[2,3-a]pyrrolo[3,4-c]quinolinones or spiroindolo[1,2-b]indazole-11,3'-pyrrolidinones is presented. Mechanistically, the formation of the title compounds involves a Rh(III)-catalyzed C-H metalation of 2-arylindazole, followed by maleimide insertion and intramolecular cyclization. Interestingly, the selectivity to form the fused or spiro compounds could be switched