Iodine-Promoted Oxidative Conversion of o-Vinyl Diaryl Ketones into o-Acetyl Diaryl Ketones, Synthesis of 1-Methyl-4-arylphthalazines as Analogues of Podophyllotoxin

A new method is described for the metal-free oxidation of o-vinyl diaryl ketones in the presence of molecular iodine or N-iodosuccinimide to give o-acetyl diaryl ketones. This transformation involves the initial formation of an iodohydrin, and the o-carbonyl group of the iodohydrin participates in a subsequent rearrangement to give the o-acetyl diaryl ketone. The presence and participation of ortho-carbonyl group is necessary for successful conversion. The envisaged 1-methyl-4-arylphthalazines were synthesized from these o-acetyl diaryl ketones, and their antiproliferative activity on mammalian cell lines was studied.