Barbituric Acid as a Substituent at Aryl Methylium Ions
作者:Stefan Spange、Mirko Bauer、Bernhard Walfort、Heinrich Lang
DOI:10.1021/jo061196+
日期:2006.9.1
Activation of different benzophenone derivatives with triflic anhydride for electrophilic aromatic substitution of 5-phenylbarbituric acids leads to regioselective formation of the ortho-substituted product. The resulting triphenylmethylium salt can be isolated when the Michlers ketone is used. More electrophilic cations form cyclic enol ethers such as 1-n-butyl-9,9-diaryl-1,9-dihydro-10-oxa-1,3-diazaphenanthrene-2