Photo-transformations of 6-chloro-3-propargyloxy-2-aryl-4-oxo-4H-1-benzopyran: 1,4-hydrogen abstraction in propargylethers

1,4-Biradicals generated in the Norrish type-II reactions of 3-propargyloxy-2-arylchromones lead to cyclisation involving the 2-aryl group. The formation and distribution of products varied with the nature of 2-aryl group.