Unique reaction of cyclicimides containing double bond with chlorosulfonyl isocyanate and theoretical computations: Solvent-free reactions

The addition reactions of chlorosulfonyl isocyanate (CSI) to N-phenylmaleimide and 2-phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione were investigated. Interesting products were obtained from the reaction of both compounds with CSI. N-phenylmaleimide led to the formation of an electrophilic substitution product, 4-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)benzenesulfonyl chloride while 2-phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione led to the formation of ((3aS,7aR,E)-3-oxo-2-phenyl-2,3,3a,4,7,7a-hexahydro-1H-isoindol-1-ylidene)sulfamoyl chloride. The structure of both products was determined by using spectroscopic methods such as NMR and Mass. Theoretical studies were carried out to explain the different reactions of both compounds with similar structures. It was determined by theoretical studies that the progression of both compounds through different reactions depends on the structure of the imides used and the energy levels of the intermediates