XY–ZH systems as potential 1,3-dipoles. Part 9. Aza-allyl anion precursors from the reaction of (1,3-dioxoindan-2-ylidene)malononitrile with α-amino acids and their methyl esters

Abstract

Glycine, valine, and α-amino acid esters react with (1,3-dioxoindan-2-ylidene)malononitrile (1) by a Michael addition–elimination mechanism with replacement of one cyano group by the α-amino acid or α-amino acid ester entity. These adducts undergo a triethylamine-catalysed stereospecific cycloaddition to N-methylmaleimide at room temperature with loss of the remaining cyano group in > 70% yield. The cycloaddition is believed to be a [3 + 2] anionic cycloaddition involving a hydrogen-bonded aza-allyl anion.