An efficient one‐pot N‐alkylation of benzimidazole and benzotriazole from carbonyl compounds and tosylhydrazide has been accomplished via copper powder‐catalyzed N—H bond insertion affording N‐alkylated products in good yields. The reaction can tolerate a wide range of carbonyl compounds, such as aryl, alkyl, heterocyclic and α,β‐unsaturated ketones, and aldehydes.
Umpolung Difunctionalization of Carbonyls via Visible-Light Photoredox Catalytic Radical-Carbanion Relay
作者:Shun Wang、Bei-Yi Cheng、Matea Sršen、Burkhard König
DOI:10.1021/jacs.0c00629
日期:2020.4.22
catalysis with the Wolff–Kishner (WK) reaction allows the difunctionalization of carbonyl groups by a radical-carbanion relay sequence (photo-Wolff–Kishner reaction). Photoredox initiated radical addition to N-sulfonylhydrazones yields α-functionalized carbanions following the WK-type mechanism. With sulfur-centered radicals, the carbanions are further functionalized by reaction with electrophiles
Ring-Opening of Indoles: An Unconventional Route for the Transformation of Indoles to 1<i>H</i>-Pyrazoles Using Lewis Acid
作者:Subhankar Panda、Nirmalya Pradhan、Debasis Manna
DOI:10.1021/acscombsci.8b00071
日期:2018.10.8
unusual transformation of indoles to pyrazoles via an aromatic ring-opening strategy has been developed. The salient feature of this strategy involves the C2–N1 bond opening and concomitant cyclization reaction of the C2═C3 bond of the indole moiety with the tosylhydrazone, which proceeds under transition-metal and ligand free conditions. This ring-opening functionalization of indoles provides a wide scope
I<sub>2</sub>-TBHP-catalyzed one-pot highly efficient synthesis of 4,3-fused 1,2,4-triazoles from N-tosylhydrazones and aromatic N-heterocycles via intermolecular formal 1,3-dipolar cycloaddition
I2-TBHP-catalyzed azomethine imine generation and subsequent regioselective 1,3-dipolarcycloaddition (DC) with aromatic N-heterocycles was developed to afford various 4,3-fused 1,2,4-triazoles in excellent yields. The method is operationally simple and highly efficient with broad functional group tolerance.
Direct Synthesis of Propen-2-yl Sulfones through Cascade Reactions Using Calcium Carbide as an Alkyne Source
作者:Lei Gao、Zhenrong Liu、Xiaolong Ma、Zheng Li
DOI:10.1021/acs.orglett.0c01915
日期:2020.7.2
A simple method for the construction of propen-2-yl sulfones through cascadereactions of calcium carbide with arylsulfonylhydrazones using copper as a mediator is described. The salient features of this protocol are the use of readily available and easy-to-handle alkyne source, broad substrate scope, open-air condition, and simple operation procedure.