When an aryl substituent is placed at C(5) of a 4-substituted cyclohexenone, a new product type involving formation of a cyclobutanone ring is formed. The reaction products are the same for both...

When an aryl substituent is placed at C(5) of a 4-substituted cyclohexenone, a new product type involving formation of a cyclobutanone ring is formed.

The reaction products are the same for both direct irradiation and acetophenone sensitization. When reactant 13-B is used in enantiomerically pure form, the product 13-D is nearly racemic (6% e.e.). Relate the formation of the cyclobutanone to the more normal products of 4-substituted cyclohexenones.