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Square flat: A new atom-economical method for the synthesis of functionalized cyclobutenes has been developed. This versatile sequence hinges upon a unique combination of an elegant photochemical isomerization and a palladium-catalyzed alkylation, and converts the readily available, “flat” aromatic 2-pyrone into a variety of functionalized products with exquisite stereoselectivity.
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Frébault et al. (2010) studied this question.
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