Photoaddition of 2-Quinolone and 2-Pyridone Derivatives to Diketene : On the Regioselectivity of the Photoaddition

Abstract

Photoaddition of 2-pyridones and 2-quinolones to diketene or allene gave the head-to-tail adducts, irrespective of the kind of 4-substituent. Therefore, the adducts obtained by the photoaddition of 2-quinolone, 4-methyl-2-quinolone, and their 1-methyl derivatives to diketene (previously assigned as having the head-to-head structure) have now been determined to have the head-to-tail structure. The stereochemistry of the adducts derived from these 2-quinolones and diketene was determined by X-ray crystallographic analysis and nuclear magnetic resonance spectroscopy.