Photochemistry of chromones: photoreorganisation of 3-alkoxy-2-thienyl-4-oxo-4H-1-benzopyrans
Abstract
Photoirradiation of a methanolic solution of 3-alkoxy-2-thienyl-4-oxo-4H-1-benzopyrans with Pyrex filtered UV light leads to cyclised and cyclodehydrogenated angular products involving both thiophene and alkoxy groups. The reaction is initiated through H-abstraction. The product distribution depends upon the substituents on the thiophene ring.