A Convenient Preparation of Xanthene Dyes.

Abstract

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.

Synthesis and Properties of V-Shaped Xanthene Dyes with Tunable and Predictable Absorption and Emission Wavelengths

“…The MOM groups in compound 22 were removed under acidic conditions, and the obtained solid was heated at 150 °C under sealed tube conditions to afford the desired V-shaped dye 7 in 54% yield over two steps. 16 In the final cyclization step, there was a concern that a dehydration reaction would proceed between the benzene ring bearing a cyano group and that bearing two hydroxy groups, which would afford a fluorescein-type compound. Fortunately, the desired cyclization reaction proceeded because cyclization with the benzene ring possessing three hydroxy groups and the highest electron density was preferred.…”