SEARCH Articles Figures Tables 1- -2-methyl-4-nitro 1- Methyl-4-nitro-5-phenylsulfonyl 2- Methyl-4 -phenylsulfonyl 2- Nitro-2-phenylsulfonyl 3-Phenylsulfonyl-5- 4 -Nitro-2-phenyl 4-Methyl-4-nitro-5-phenyl-5- 5-Phenyl-3-phenylsulfonyl