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14.4.10.1.2.1.1.1 Method 1: Cycloaddition of 3-(Phenylsulfinyl)-4H-1-benzopyran-4-ones and Danishefsky's Diene

DOI: 10.1055/sos-SD-014-00294

Williams, A. C.; Camp, N.Science of Synthesis, (200314604.

A cycloadditionelimination sequence is used in the synthesis of 3-hydroxy-9H-xanthen-9-one (686) (Scheme 268).[‌1042‌] In this reaction, 3-(4-chlorophenylsulfinyl)-4H-1-benzopyran-4-one undergoes a cycloaddition with 1-methoxy-3-(trimethylsiloxy)buta-1,3-diene (Danishefsky's diene) in refluxing 1,2-dimethoxyethane to produce an intermediate that eliminates 4-chlorobenzenesulfenic acid and methanol to provide the desired product 686 as a single regioisomer in 50% yield.

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