Reaction of 2-diazopropane with an arylsulphonyl-trimethylsilyl substituted alkene. Steric control of regiochemistry by the trimethylsilyl group

The 1,3-dipolar cycloaddition of 2-diazopropane with trimethyl[3-(p-tolylsulphonyl-2,5-norbornadiene-2-yl)]silane occurs across the unsubstituted double bond; regiochemical control can be attributed to steric rather than to stereoelectronic factors.