3-Unsubstituted 1,5-Diaryl-2,4-pentanediones and -4-methoxy-2-pentanones: Synthesis via Corresponding 3-Hydroxy Ketones Generated from 2-Isoxazolines

Aryl acetaldoximes are reacted with allylarenes in the presence of sodium hypochlorite to give 3,5-bis(arylmethyl)-2-isoxazolines which are then converted to 1,5-diaryl-4-hydroxy-2-pentanones by a reductive hydrogenation in the presence of water. These intermediate aldols can then be either oxidized with Corey−Kim reagent to stable dimethylsulfonium 1-(arylacetyl)-2-oxo-3-arylpropylides followed by zinc−acetic acid reduction to give 1,5-diaryl-2,4-pentanediones, or converted to 1,5-diaryl-4-methoxy-2-pentanones by refluxing in methanol in the presence of hydrochloric acid. A detailed study of this general route is reported here.