A general route to fluorinated 3,3-disubstituted 2-oxindoles via a photoinduced radical cyclization of N-arylacrylamides under catalyst-free conditions

A catalyst-free radical cyclization of N-arylacrylamides with fluorinated alkyl iodides or the Togni reagent enabled by photoenergy is reported, leading to fluorinated 2-oxindoles in good yields. The broad reaction scope is demonstrated with good functional group tolerance.

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Metal-Free Radical Cyclization of Vinyl Isocyanides with Alkanes: Synthesis of 1-Alkylisoquinolines

Synthesis ◽

10.1055/s-0037-1610661 ◽

2018 ◽

Vol 51 (04) ◽

pp. 874-884 ◽

Cited By ~ 3

Author(s):

Liming Shao ◽

Dengqi Xue ◽

Yijie Xue ◽

Haihua Yu

Keyword(s):

Free Radical ◽

Isotope Effect ◽

Kinetic Isotope Effect ◽

Functional Group ◽

Radical Cyclization ◽

Diverse Range ◽

Radical Process ◽

Metal Free ◽

Kinetic Isotope ◽

Inhibition Studies

A metal-free radical cyclization reaction of vinyl isocyanides with alkanes is developed, allowing convenient access to a diverse range of potentially valuable 1-alkylisoquinolines. The methodology is simple and efficient, demonstrating excellent functional group tolerance and broad substrate scope. A mechanism involving a radical process is supported by kinetic isotope effect and radical inhibition studies.

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Free Radical Cyclization of N-Arylacrylamides: Mild and Facile Synthesis of 3-Thiocyanato Oxindoles

Synlett ◽

10.1055/s-0036-1591927 ◽

2018 ◽

Vol 29 (07) ◽

pp. 954-958 ◽

Cited By ~ 6

Author(s):

Fu-Xue Chen ◽

Pran Karmaker ◽

Jiashen Qiu ◽

Di Wu ◽

Hongquan Yin

Keyword(s):

Free Radical ◽

Functional Groups ◽

Functional Group ◽

Radical Cyclization ◽

Facile Synthesis ◽

Oxidative Radical Cyclization ◽

Operational Simplicity ◽

Convenient Access

A novel and convenient oxidative radical cyclization of N-substituted N-arylacrylamides for the synthesis of 3-thiocyanated oxindoles has been developed by using AgSCN and K2S2O8 as the radical source. This process allows a consistent and convenient access to SCN-containing heterocycles bearing a broad range of functional groups in good to excellent yields (up to 91%). Moreover, the use of inexpensive and readily available starting materials, operational simplicity, and excellent functional group tolerance makes this protocol practically attractive.

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Radical Cyclization of Olefinic Amides through α-C(sp3)–H Functionalization of Ketones under Catalyst-, Ligand-, and Base-Free Conditions

Synlett ◽

10.1055/a-1468-5962 ◽

2021 ◽

Author(s):

Yiping Ruan ◽

Hongxin Liu ◽

Wen-Ting Wei ◽

Fu-Hua Qin ◽

Qing-Qing Kang ◽

...

Keyword(s):

Functional Group ◽

Free Ligand ◽

Radical Cyclization ◽

Mechanistic Study ◽

Tert Butyl ◽

Catalyst Free ◽

Wide Range ◽

Ligand Free ◽

First Time ◽

Carbonyl Radical

AbstractA new, efficient, and practical radical cyclization of olefinic amides with ketones through α-C(sp3)–H functionalization in the presence of tert-butyl peroxybenzoate (TBPB) is described for the first time. This protocol assembles a wide range of pivotal and useful benzoxazines in good to excellent yields under mild, catalyst-free, ligand-free, and base-free conditions with wide functional group tolerance. Moreover, the mechanistic study indicates that the α-carbonyl radical is involved in this transformation.

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Facile 5-endo ring closures to the azo group. A free radical synthesis of indazoles

Canadian Journal of Chemistry ◽

10.1139/v90-088 ◽

1990 ◽

Vol 68 (4) ◽

pp. 575-580 ◽

Cited By ~ 25

Author(s):

Cheryl P. A. Kunka ◽

John Warkentin

Keyword(s):

Free Radical ◽

Rate Constants ◽

Functional Group ◽

Radical Cyclization ◽

Double Bonds ◽

Aryl Radicals ◽

Azo Group ◽

Group A ◽

Radical Clock

Five 1-alkyl-3-methylindazoles were prepared by treatment of 1-(2-bromophenyl)-1-methoxy-1-(2-alkylazo)ethanes with tri-n-butyl stannane and AIBN at 80 °C in benzene. Yields in the radical cyclization step ranged from 39 to 92%. 1-Phenyl-3-methylindazole was prepared by an analogous route but in very poor yield (<5%). Rate constants for the 5-endo radical closures [Formula: see text], estimated by the radical clock method, were 5.2 × 109 s−1 and 9.2 × 108 s−1 for two of the alkyl systems. Rate constants for analogous 5-endo cyclizations of aryl radicals onto C—C double bonds are much smaller than those for cyclizations to the azo functional group. Keywords: cyclization, radical; azo group, radical closure to; indazoles, radical synthesis of.

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Metal-Free Photoinduced Hydroalkylation Cascade Enabled by an Electron-Donor-Acceptor Complex

10.26434/chemrxiv.11912073 ◽

2020 ◽

Author(s):

José Tiago Menezes Correia ◽

Gustavo Piva da Silva ◽

Camila Menezes Kisukuri ◽

Elias André ◽

Bruno Pires ◽

...

Keyword(s):

Electron Donor ◽

Functional Group ◽

Photoexcited Electron ◽

One Pot ◽

Quaternary Centers ◽

Metal Free ◽

Acceptor Complex ◽

Catalyst Free ◽

Donor Acceptor ◽

Radical Cascade

A metal- and catalyst-free photoinduced radical cascade hydroalkylation of 1,7-enynes has been disclosed. The process is triggered by a SET event involving a photoexcited electron-donor-aceptor complex between NHPI ester and Hantzsch ester, which decomposes to afford a tertiary radical that is readily trapped by the enyne. <a>The method provides an operationally simple, robust and step-economical approach to the construction of diversely functionalized dihydroquinolinones bearing quaternary-centers. A sequential one-pot hydroalkylation-isomerization approach is also allowed giving access to a family of quinolinones. A wide substrate scope and high functional group tolerance was observed in both approaches</a>.

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