Synthesis of Di- and Tetra-Sulfonated Heterocyclic Compounds by Crisscross Cycloaddition Reactions

Using sulfonated diaryl azines and sulfonated N-arylmaleimides as starting reagents, a range of di- and tetra-sulfonated crisscross cycloadducts were selectively prepared. While the di-sulfonated adducts were obtained by carrying out the cycloaddition reaction in solution, the tetra-sulfonated adducts could be obtained only by fusion of the two reagents in the absence of solvent. The stereoisomers of the sulfonated cycloadducts were separated by preparative TLC.

Keywords:

• Crisscross cycloadducts
• sulfonamides
• sulfonates

Acknowledgments

Thanks are due to the University of Aveiro and Fundação para a Ciência e a Tecnologia (FCT, Portugal) and FEDER for funding the Organic Chemistry Research Unit. The authors thank Prof. A. M. S. Silva (University of Aveiro) for his invaluable assistance in the NMR experiments.