2-Amino-1,2,3,6-tetrahydro-6-oxocyclopenta[c]fluorene-2-carboxylic acid (FlAib), a completely rigidified, fluoren-9-one-based alpha-amino acid

The synthesis, optical resolution, determination of absolute configuration and conformational preference, and spectroscopic characteristics of terminally protected (blocked) derivatives and short peptides of 2-amino-1,2,3,6-tetrahydro-6-oxocyclopenta[c]fluorene-2-carboxylic acid (FlAib), a novel, rigid, chiral, cyclized C-alpha,alpha-disubstituted glycine are described.