We have discovered that: 1) unprotected and carbamate-protected aziridines and azetidines undergo efficient ring-opening reactions in liquid SO2 with I and II group metal halides and thiols; 2) liquid SO2 facilitates the Ritter reaction; 3) liquid SO2 in combination with In(OTf)3 or Hf(OTf)4 (< 1 mol-%) greatly facilitates alkyne hydration; 4) alkyne hydrohalogenation in liquid SO2 with I and II group metal halides and NH4X does not require Lewis acid catalysis. We have also developed catalytic conditions for synthesis of trialkylsilyl allylsulfinates in ene-reactions between allylsilanes and SO2. The obtained products can be used for both preperative and GC derivatization.