A Convenient Preparation of Xanthene Dyes

A facile synthetic route utilizing readily available reagents affords a series of regioisomerically
pure xanthene dye derivatives. Advantages include relatively mild conditions and good to excellent
yields. Nonpolar, highly crystalline intermediates are isolable by standard chromatographic
techniques. The intermediates are in the requisite xanthene oxidation state, thus avoiding the
need for relatively inefficient oxidation chemistry and/or harsh conditions. During the course of
this work, a new boron-mediated 1,2-aryl migration reaction was discovered.