Regioselective rearrangement of 7-azabicyclo[2.2.1]hept-2-aminyl radicals: first synthesis of 2,8-diazabicyclo[3.2.1]oct-2-enes and their conversion into 5-(2-aminoethyl)-2,3,4-trihydroxypyrrolidines, new inhibitors of α-mannosidases

Abstract

Enantiomerically pure 2,8-diazabicyclo[3.2.1]oct-2-ene derivatives (+)- 5 and (−)- 5 have been obtained from 2-azido-3-tosyl-7-azabicyclo[2.2.1]heptanes (+)- 1 and (−)- 2 and their enantiomers, by ring expansion under radical conditions. Compounds (+)- 5 and (−)- 5 were transformed into hemiaminals 9 ((3 S,4 R,5 R)- and 10 ((3 R,4 S,5 S)-5-(2-aminoethyl)-2,3,4-trihydroxypyrrolidine) that are good inhibitors of α-mannosidases.