C¹-Substituted N-tert-butoxycarbonyl-5-syn-tert-butyldimethylsilyloxymethyl-2-azabicyclo[2.1.1]hexanes as conformationally constrained β-amino acid precursors

Regioselective introduction and transformation of substituents at the C¹ carbon of N-tert-butoxycarbonyl-5-syn-tert-butyldimethylsilyloxymethyl-2-azabicyclo[2.1.1]hexane (7) is described. These azabicycles are precursors to conformationally constrained β-amino acids with potential to form oligomers with definite secondary structures. Selected examples of these precursors are converted into their corresponding amino acid derivatives.