Antiaromatic dianions: Dianions of dixanthylidene by reduction and attempted excited-state deprotonation

摘要

Reduction of dixanthylidene with potassium or lithium resulted in formation of the antiaromatic dianion in high yield. Attempts to form the dianion by excited-state deprotonation of dixanthene with n-butyllithium/TMEDA resulted in formation of the tetraanion from deprotonation ortho to the oxygen. Orientation of the sp3 hydrogens presumably allows preferential deprotonation of the xanthene rings.