89346-77-0Relevant academic research and scientific papers
Synthesis of 3-(Tosylalkyl)indazoles and their desulfonylation reactions a new entry to 3-substituted indazoles by an unprecedented friedel-crafts process
Campetella, Silvia,Palmieri, Alessandro,Petrini, Marino
experimental part, p. 3184 - 3188 (2009/12/07)
Reaction of indazoles with aldehydes in the presence of ptoluenesulfinic acid affords the corresponding sulfonyl indazoles in satisfactory yields. The reported Friedel-Crafts process is rather unusual on indazoles because of the reduced electronic density
Phase-Transfer-Catalyzed Gomberg-Bachmann Synthesis of Unsymmetrical Biarenes: A Survey of Catalysts and Substrates
Beadle, James R.,Korzeniowsky, Stephen H.,Rosenberg, David E.,Garcia-Slanga, Blanche J.,Gokel, George W.
, p. 1594 - 1603 (2007/10/02)
Two problems have hindered the Gomberg-Bachmann (GB) and Pschorr reactions of arenediazonium cations: the instability of the arenediazonium salts and side reactions.Arenediazonium tetrafluoroborate and hexafluorophosphate salts can be prepared in high yield and purity and can be stored safely.Unfortunately, these salts are insoluble in most nonpolar organic solvents.Crown ether complexation or other phase-transfer (pt) catalytic methodology can ameliorate this situation, and reactions conducted by the approaches outlined herein often afforded coupling or cyclization products in high yield and corresponding purity.The use of crown ethers, quarternary 'onium salts, lipophilic carboxylic acid salts, and even the polar cosolvent acetonitrile increase the utility of the ptGB reaction dramatically.Sixty examples of couplings are reported along with an assessment of selectivities.A number of examples are also presented of phase-transfer-type Pschorr cyclizations.In the latter case, the use of potassium superoxide, KO2, is introduced to suppress indazole formation.
