Synthesis of enantiomerically pure 1,2-diamine derivatives of 7-azabicyclo[2.2.1]heptane. New leads as glycosidase inhibitors and rigid scaffolds for the preparation of peptide analogues

Enantiomerically pure alcohols (-)- and (+)-7-tert-butoxycarbonyl-6-endo-p-toluenesulfonyl-7azabicyclo[2.2.1]hep t-2-en-5-endo-ol ((-)-11 and (+)-11) have been obtained from the Diels-Alder adduct of N-(tert-butoxycarbonyl)pyrroel and 2-bromo-1-p-toluenesulfonylacetylene, including a resolution method. These two alcohols were converted into (+)- and (-)-5-exo-amino-7-(tertbutoxycarbonyl))-2,3-exo-isopropylidenedioxy-7-az abicyclo[2.2.1]heptane ((+)-18 and (-)-18) and (+)and (-)-5-endo-amino-7-(tert-butoxycarbonyl)-2,3-exo-isopropylidenedioxy-7-a zabicyclo[2.2.1]heptane ((+)-19 and (-)-19) after adequate fanctionalization and desulfonylation steps. The corresponding conformationally constrained bicyclic 1,2-diamines (+)-4, (-)-4, (+/-)-5, (+/-)-6, (+)-7, and (-)-7 were obtained from the protected precursors 18 and 19 and evaluated as glycosidase inhibitors. Diamines (+)-4, (-)-4, (+)-6, and (-)-6 can be seen as new nonpeptide molecular scaffolds for the design of peptide analogues.