Structure of the products of the cyclooligomerization of sulfur dioxide with diethyl diallylmalonate

The AIBN-initiated cooligomerization of sulfur dioxide with diethyl diallylmalonate in the presence of bromotrichloromethane or thiophenol was investigated, ES/MS and NMR studies show that 1:1 cooligomers of cis-linked 5-membered rings are formed, Electrospray mass spectrometry demonstrates that, in the case of CCl3Br, the end group is -CH2Br, and C-13 NMR demonstrates that the other end group is -Cl2CCl3, The thiophenol reaction leads to end groups of either -CH3 or -CH2SO2H with PhSCH2 at the other end. The molecular weight of oligomers was inversely proportional to the concentration of the chain-transfer agent. The polymerization chain transfer constants for bromotrichloromethane and thiophenol are 4.63 x 10(-4) and 8.10 x 10(-4), respectively, at 81 degrees C.