A facile synthetic approach to 3'-substituted-5-cyclopropanespirohydantoins has been developed and used to synthesize some new spirohydantoins. The key aspect is the preparation of -carboethoxy isocyanate basing on Curtius rearrangement, which can be ring-closed to the expected spirohydantoins after the reaction with various amines and hydrazines. Interestingly the cyclopropane ring doesn't open during the whole process.

A series of dihydropyrrolones were synthesized in high yields by reaction of two same/different primary amines, but-2-ynedioates and formaldehyde in the presence of sulfuric acid-modified polyethylene glycol 6000 in MeOH at room temperature. All products were characterized by 1 H NMR, 13 C NMR, IR and elemental analysis.