Methylthiomethylation and subsequent sulfoxidation and pyrolysis of the N-Boc-protected β³-amino acid methyl esters derived from Ala, Val, and Leu provided the α-methylene esters; these were then used to synthesize the β-peptides specified in the title (step-by-step and fragment coupling in solution). The novel β-peptides were fully characterized, but neither solid-state nor solution structures were found.