An Easy Access to 1-Azaspiropentane-2-carboxamides – The First Derivatives of a New Type of Amino Acids

Azaspiropentanecarboxamides 10 and 12 are formed with remarkable ease in two steps in a one-pot operation from methyl 2-chloro-2-cyclopropylideneacetate (4) by addition of a primary amine in tetrahydrofuran and subsequent treatment with sodium hydride/triethylamine in the presence of another equivalent of a primary amine or ammonia. Achievable yields of the amides 10, 12 were moderate to good (27–59%, 12–48%), while the corresponding esters 9 could only be obtained in poor yields (4–14%). The new α-amino acid amides are surprisingly stable, and they can be incorporated into small peptides as demonstrated with the preparation of the glycine 13e and the spirocyclopro-paneoxazoline derivative 14e.