Science of Synthesis

Williams, A. C.; Camp, N., Science of Synthesis, (2003) 14, 603.

Treatment of 2-phenoxybenzaldehydes with copper(II) halides in refluxing nitrobenzene gives an interesting method for 9H-xanthen-9-one ‌685‌ syntheses (‌Scheme 267‌).[‌1041‌] The postulated mechanism involves thermal decomposition of the copper(II) halide to provide copper(I) halide plus a halide radical that reacts with the aldehyde to form an acyl radical. This acyl radical cyclizes oxidatively to produce the 9H-xanthen-9-one and in the process hydrogen chloride or hydrogen bromide is generated.

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