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7663222 
Journal Article 
SOLUBLE CATALYSTS FOR IMPROVED PSCHORR CYCLIZATIONS 
Wassmundt, FW; Kiesman, WF; , 
1995 
Yes 
Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904 
AMER CHEMICAL SOC 
WASHINGTON 
60 
1 
196-201 
English 
WOS:A1995QC16000033 
Several improved catalysts for the Pschorr phenanthrene synthesis have been discovered; all are soluble substances which initiate free-radical reactions by electron donation and thereby shorten the reaction time and increase the yield. One technique with K4Fe(CN)(6) in water produced phenanthrene-9-carboxylic acid (6a) in 87% yield, but its application did not extend to substituted examples where the diazonium salt is less soluble in water. A more general procedure with ferrocene in acetone produced not only 6a but also substituted examples 6b-f in yields of 88-94%. A modification which avoids the isolation of diazonium salts was developed for occasional synthetic use.