Chromanones synthesis, Friedel-Crafts reaction

This year has seen the publication of the first convenient synthesis of crotonophenones, which are open chain forms of benzopyranones (chromanones). Previous attempts at their synthesis via Friedel-Crafts or simple aldol reactions gave poor yields. However, it has now been shown that the dianion of n-hydroxyacetophenones will react with aldehydes, and dehydration of the products constitutes a simple synthesis of crotonophenones and also of 2-methyl chromanones. 

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