Wittig reactions of chromone-3-carboxaldehydes with benzylidenetriphenyl phosphoranes: a new synthesis of 3-styrylchromones

An efficient route to 3-styrylchromones has been developed and applied to syntheses of several new derivatives. Wittig reactions of chromone-3-carboxaldehydes with some benzylic ylides gave a diastereomeric mixture of (E) and (Z)-3-styrylchromones that are separable by thin layer chromatography. The (Z)-isomers were the most abundant diastereomers independent of having electron-withdrawing or electron-donating substituents on the phenyl ring. Stereochemistry of the obtained diastereomers was established using NOESY experiments.