A Series of Two Oxidation Reactions of ortho-Alkenylbenzamide with Hypervalent Iodine(III): A Concise Entry into (3R,4R)-4-Hydroxymellein and (3R,4R)-4-Hydroxy-6-methoxymellein

A sequence of oxidation reactions of alkenamides with hypervalent iodine is described. Oxidation of ortho-alkenylbenzamide substrates selectively gave isochroman-1-imine products. The products underwent further oxidation in the presence of a Pd salt catalyst leading to regioselective C-H acetoxylation at the 8-position. A series of oxidations was applied to the crucial steps of asymmetric synthesis of 4-hydroxymellein derivatives.