Unprecedented access to the parent trans-cyclobutane β-aminoacid in enantiomerically pure form(Abstracts)

摘要

β-Amino acids attract considerable attention due to their role as key components in a wide variety of biologically-active natural and synthetic peptides and their ability to induce fascinating regular folding structures in oligopeptides. Alicyclic β-aminoacids are of special interest, due to the severe conformational constraints present in these materials. Within this family, studies on 2-amino-cyclobutanecarboxylic acids (ACBCs) have been hampered due to their limited availability. Recently, we established a rapid entry to the cis-ACBC skeleton, based on the [2+2] photo-cycloaddition of ethylene with a uracil derivative An extension of this approach using a chirally-adapted uracil provides enantiomerically pure cis-ACBC. Access to trans-ACBCs remains a problem, however, and the parent compound has never been described in enantiomerically pure form.