Facilitated Intramolecular Conjugate Addition of N-(p-Methoxyphenyl)-3-(3',6'-dioxo-2',4'-dimethylcyclohexa-1',4'-dienyl)-3,3-dimethylpropionamide. 1. Product Characterization

Article abstract of DOI:10.1021/jo00049a018

N-(p-Methoxyphenyl)-3-(3',6'-dioxo-2',4'-dimethylcyclohexa-1',4'-dienyl)-3,3-dimethylpropionamide (1), a pro-prodrug model, was chosen to study the reaction of quinone propionic amides in mildly acidic aqueous solution.The quinone propionic amide 1 equilibrates rapidly with its hydroxy dienone 6 and undergoes a much slower 1,4 conjugate addition to form its enol spirolactam 4.The enol spirolactam 4 then tautomerizes to give the keto spirolactam 5.Spectroscopic evidence suggests that the keto spirolactam 5 is present as a diastereomeric mixture, wherein the preferred diastereomer has the 2'-methyl and the lactam nitrogen anti to each other.