Synthesis of Conformationally Constrained Dipeptide Mimetics with Azabicyclo[4,3,0]nonanone and Azabicyclo[5,3,0]decanone Scaffolds

A general and efficient method for the synthesis of azabicyclo[4,3,0]nonanone and azabicyclo[5,3,0]clecanone amino acid derivatives was developed with the palladium-catalyzed coupling of intermediates 9 and 10 with BocNH(2) and Boc(2)NH and the following reduction of the C-C double bond by hydrogenation as the key steps. The exploration of the synthesis of C-6-substituted dipeptide mimetics from 9 and 10 using Suzuki coupling as the key reaction has also been performed.