Unusual recyclization of 2-methyl-1-phenyliso- quinolinium iodide to 1-phenyl-1,4-dihydro- 3h-isochroman-3-one
The formation of an isochroman-3-one was unexpectedly observed during the course of studying the rearrangement of 1-substituted isoquinolinium salts in the presence of O-nucleophiles. Hence refluxing 2-methyl-1-phenylisoquinolinium iodide (1) with a solution of sodium hydroxide in alcohol and subsequent treatment with acid gave a high yield of the 1-phenyl-1,4-dihydro-3H-isochroman-3-one (2). It was found that compound 2 is only formed after the acidification of the reaction mixture at the separation stage.