Synthesis of gem-disubstituted taurines by the regioselective ring-opening of 2,2-disubstituted aziridines with sodium bisulfite and sulfite

The regioselectivity of the ring-opening reactions of 2,2-disubstituted aziridines with sodium bisulfite and sulfite showed significant divergence depending on the nucleophiles and the structure of the substituents of the aziridines. 2,2-Dialkylaziridines were specifically attacked on their less substituted carbon atoms with sodium bisulfite, affording 2,2-substituted taurines, while 2,2-disubstituted aziridines with either one or two aryl substituent(s) were attacked specifically on their more substituted carbon atoms with the same nucleophile, giving rise to aromatic 1,1-substituted taurines. Sodium sulfite attacked the less substituted carbon atoms of all aziridines specifically to afford 2,2-disubstituted taurines. The regioselectivity is governed by the nucleophile and the balance between the steric hindrance and the electronic effect. The current method provides an alternative route to the synthesis of 2,2-dialkyltaurines and aromatic gem-disubstituted taurines.