Highly substituted pyrrolidinones and pyridones by 4-CR/2-CR sequence

By combining a Ugi four-component reaction of isocyanides, phosphonoacetic acids, primary amines, and glyoxals or alternatively 3-keto aldehydes with a subsequent Wittig ring-closing reaction (using the Horner/Wadsworth/Emmons variant (HWE)), highly substituted 5-oxo-2,5dihydro-1H-pyrrole-2-carboxylic acid amides and 6-oxo-1,2,3,6-tetrahydro-pyridine-2-carboxylic acid amides can be assembled, respectively. The corresponding tandem of a Passerini reaction on 3-keto aldehydes and subsequent Wittig ring closure does not afford the expected six-membered 6-oxo-3,6-dihydro-2H-pyran-2-carboxylic acid amides but instead leads to the formation of 4-oxo-pent-2-enoic acid amides via an elimination route.