Synthesis of Linearly and Angularly Fused Indane-Based Constrained α-Amino Acid Derivatives

The benzocyclobutene-based alpha-amino acid derivative, ethyl 5-acetamido-2,4,5,6-tetrahydro-1H-cyclobuta[f] indene-5-carboxylate is synthesized via coupling of a benzocyclobutene-derived dibromide with ethyl isocyanoacetate as the key step, followed by hydrolysis and subsequent acetylation. This methodology is generalized in order to prepare various linearly and angularly fused indane-based alpha-amino acid derivatives.