Standard N-Boc protection of amine 26a (via Boc-26a), followed by the Staundinger reaction gave bromide 37. Swern oxidation of alcohol Boc-26a gave aldehyde 38 that was subsequently oxidized into N-Boc protected amino acid 39 (Scheme 6). Using this tactic, alcohol 3a was easily converted into N-Boc amino acid 40. Amino acids 41-43 were synthesized analogously.