Deprotection of sulfonyl aziridines

The deprotection of the chiral N-sulfonyl aziridines 1-3 has been studied u nder different desulfonylation conditions. Two methods for the efficient de protection of 2-benzyl-, 2-phenyl-, and 2-carboxyl-N-sulfonylaziridines wer e found. The desulfonylation with lithium and a catalytic amount of di-tert -butyl biphenyl in THF at -78 degrees C led to the corresponding NH aziridi nes with yields up to 85%. Alternatively, the desulfonylation could be carr ied out with magnesium in methanol under ultrasonic conditions. The latter proved to be avery mild method and afforded the desulfonylated aziridines w ith yields up to 75%, even when the 2-phenyl substituted aziridine 2 was th e studied substrate. Furthermore, in all the cases studied, no racemization was observed in the chiral center of the aziridines.