Science of Synthesis

Williams, A. C.; Camp, N., Science of Synthesis, (2003) 14, 595.

A simple method for the synthesis of 2-substituted 9H-xanthen-9-ones from diphenyl ethers involves dilithiation followed by carboxylation.[‌1004‌] Treatment of the diphenyl ether with butyllithium in diethyl ether under reflux for three days provides a dilithiated species that can be quenched with carbon dioxide to provide the desired 9H-xanthen-9-one. This metalation is highly regioselective and gives moderate to good yields of 2-substituted 9H-xanthen-9-ones ‌673‌ (‌Scheme 255‌). The main side product, bis(2-phenoxyphenyl)methanone (22%) is the result of a competing intermolecular reaction.

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