BF3 x OEt2-mediated highly regioselective S(N)2-type ring-opening of N-activated aziridines and N-activated azetidines by tetraalkylammonium halides.

A highly regioselective Lewis acid-mediated S(N)2-type ring-opening of N-sulfonylaziridines and azetidines with tetraalkylammonium halides in CH(2)Cl(2) solution to afford 1,2- and 1,3-haloamines in excellent yields is described. An easy diastereoselective route toward substituted chiral N-tosylaziridines has been developed. The mechanism of ring-opening via S(N)2 pathway has been confirmed by the formation of chiral haloamines with excellent er and dr. Chloroamines obtained from 2,3-disubstituted aziridines were converted to the chiral N-tosylamines via radical dehalogenation.