1,3-DIPOLAR CYCLOADDITION CHEMISTRY OF 2,3-BIS(PHENYLSULFONYL)-1,3-DIENE WITH DIAZOALKANES

2,3-Bis(phenylsulfonyl)-1,3-butadiene was found to react smoothly with diazomethane and diazopropane to give a mixture of 1:1- and 2:1-cyclo adducts. Heating the 1:1-cycloadduct at 110 degrees C resulted in loss of nitrogen and formation of mainly phenylsulfonyl-substituted 1,3-di enes. Cycloaddition of 2-phenylsulfinyl-3-phenylsulfonyl-1,3-butadiene with the same diazoalkanes gave only 1:1-cycloadducts which readily e xtruded nitrogen producing related 1,3-dienes. The regiochemistry of t he dipolar cycloaddition is compatible with FMO considerations.