Silicon Carbide Passive Heating Elements in Microwave-Assisted Organic Synthesis
作者:Jennifer M. Kremsner、C. Oliver Kappe
DOI:10.1021/jo060692v
日期:2006.6.1
Microwave-assisted organic synthesis in nonpolar solvents is investigated utilizing cylinders of sintered silicon carbide (SiC)a chemically inert and strongly microwave absorbing materialas passive heating elements (PHEs). These heating inserts absorb microwave energy and subsequently transfer the generated thermal energy via conduction phenomena to the reaction mixture. The use of passive heating
Chemo-, Regio-, and Stereoselective <i>N</i>-Alkenylation of Pyrazoles/Benzpyrazoles Using Activated and Unactivated Alkynes
作者:Vineeta Garg、Pradeep Kumar、Akhilesh K. Verma
DOI:10.1021/acs.joc.7b01746
日期:2017.10.6
Transition-metal-free chemo-, regio-, and stereoselective synthesis of (Z) and (E) styryl pyrazoles and benzpyrazoles by the addition of N-heterocycles onto functionalized terminal and internal alkynes using a super basic solution of KOH/DMSO has been described. The stereochemical outcome of the reaction was governed by time and quantity of the base. The reaction of pyrazoles and benzpyrazoles onto
Synthesis of Fluorescent Indazoles by Palladium-Catalyzed Benzannulation of Pyrazoles with Alkynes
作者:Og Soon Kim、Jin Hyeok Jang、Hyun Tae Kim、Su Jin Han、Gavin Chit Tsui、Jung Min Joo
DOI:10.1021/acs.orglett.7b00410
日期:2017.3.17
pyrazoles and internal alkynes is described. Instead of complex benzenoid compounds, readily available pyrazoles were used for the preparation of indazoles by reaction of the C–H bonds of the heterocyclic ring. Oxidative benzannulation was also applied to imidazoles, providing benzimidazoles. This convergent strategy enabled alteration of the photochemical properties of benzo-fused diazoles by varying the
<scp>Palladium‐catalyzed</scp>
Aerobic Benzannulation of Pyrazoles with Alkynes
作者:Jae Yeong Song、Jin Hyeok Jang、Shih‐Ching Chuang、Jung Min Joo
DOI:10.1002/bkcs.12175
日期:2021.3
stoichiometric metal oxidant, oxygen was used as an oxidant for Pd‐catalyzed annulation reactions of pyrazoles with internal alkynes. The addition of sodium acetate and acetic acid was critical for stabilizing the Pd system. This green approach allowed the preparation of indazoles from readily available parent pyrazoles in a single step.
Sintered Silicon Carbide: A New Ceramic Vessel Material for Microwave Chemistry in Single-Mode Reactors
作者:Bernhard Gutmann、David Obermayer、Benedikt Reichart、Bojana Prekodravac、Muhammad Irfan、Jennifer M. Kremsner、C. Oliver Kappe
DOI:10.1002/chem.201001703
日期:2010.10.25
Siliconcarbide (SiC) is a strongly microwave absorbing chemically inert ceramic material that can be utilized at extremely high temperatures due to its high melting point and very low thermal expansion coefficient. Microwave irradiation induces a flow of electrons in the semiconductingceramic that heats the material very efficiently through resistance heating mechanisms. The use of SiC carbide reaction