Role of temperature in [3+2]-cycloaddition of isoselenocyanates with oxiranes using BF3•Et2O

The [3+2]-cycloaddition reaction of isoselenocyanates with oxiranes using BF3 center dot Et2O is temperature dependent affording generally either substituted 2-imino-1,3-oxaselenolanes (-5 degrees C) or 1,3-oxazolidinones (40 degrees C) in short reaction times with high yields.