Site- and Regioselectivity of Nitrile Oxide-Allene Cycloadditions : DFT-Based Semiquantitative Predictions

Nitrile oxide 1,3-dipolar cycloaddition to arylsulfonyl- and dialkylaminoallenes have been investigated within the framework of the Kohn-Sham density functional theory (DFT) at the B3LYP/6-31G(d,p) level. The hitherto-unexplained experimental behavior of sulfonylallenes was rationalized by transition-state calculations which enabled a semiquantitative treatment of the cycloaddition site- and regioselectivity. The reliability of DFT computations was further established by predicting the complete selectivity of the nitrile oxide cycloaddition to dialkylaminoallenes according to previous experimental findings.