Synthesis of Tritylones via Cascade Reaction of Arynes with 5-Ethoxyoxazoles

A cascade reaction involving arynes and 5-ethoxyoxazoles has been developed toward the synthesis of 9-alkyl/aryl tritylones. 5-Ethoxyoxazoles undergo a [4 + 2]cycloaddition reaction with arynes followed by retro-[4 + 2]cycloaddition, a second intermolecular [4 + 2] cycloadditionreaction, and hydrolytic ring cleavage to generate substitutedtritylones in good yields. The conversion of tritylone products to aseries of spirocyclic anthrone derivatives has been demonstrated. The reaction is expeditious, exhibits wide scope, and employsreadily available starting materials.

Automated summary

A cascade reaction involving arynes and 5-ethoxyoxazoles has been developed for the synthesis of 9-alkyl/aryl tritylones, which demonstrates high yields and efficient conversion to a series of spirocyclic anthrone derivatives.