Science of Synthesis

Marsden, S. P., Science of Synthesis, (2005) 26, 1100.

Furans can be transformed to enediones by oxidative ring opening. A variety of reagents can be used for this transformation, but the reaction is only stereospecific (for the formation of the Z-isomer ‌319‌) when the oxidant is a peracid or synthetic equivalent (‌Scheme 55‌).[‌247‌] The reactions are particularly useful when the furan bears a 2- or 5-substituent with an α-hydroxy or α-amino group, since these add to the distal carbonyl upon ring opening to generate respectively dihydropyranones and pyridinones. The use of the Sharpless asymmetric epoxidation protocol in kinetic resolution mode allows for formation of enantioenriched furyl alcohols (e.g., ‌320‌)[‌248‌] and amines (e.g., ‌322‌).[‌249‌] Oxidative ring opening of these enantiomerically enriched substrates provides access to useful chiral dihydropyranone ‌321‌ and dihydropyridinone ‌323‌ building blocks for synthesis.

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