A safe and efficient synthesis of N-Boc-β3-amino acid methyl esters from α-amino acids: applications in the formal synthesis of sedum alkaloids†

β³-Amino acids are essential components in the synthesis of biologically active compounds. However, obtaining them in enantiomerically pure forms remains challenging. This study investigates a safe and efficient method for synthesizing enantiopure N-Boc-β³-amino acid methyl esters, incorporating both natural and unnatural side chains. The procedure avoids the use of expensive and toxic reagents, providing a safer alternative to the hazardous Arndt–Eistert homologation and cyanation reactions, which typically begin with enantiopure α-amino acids. The practical value of this transformation was demonstrated in the formal synthesis of sedum alkaloids.