Synthesis of enantiopure protected 3-hydroxy-4-amino pyrroline N-oxides

The synthesis of new five-membered enantiopure cyclic nitrones bearing protected cis vicinal amino and hydroxy functionalities is reported. The key step was a Mitsunobu reaction, which allowed placement of an azido group, with inversion of configuration, at the reacting centre. Cycloaddition of the novel nitrones to but-3-en-1-ol followed by simple elaboration of the adducts readily afforded protected amino dihydroxy indolizidines.