A sustainable strategy for the synthesis of bis-2-iminothiazolidin-4-ones utilizing novel series of asymmetrically substituted bis-thioureas as viable precursors.

A novel series of asymmetrically substituted bis-thioureas has been synthesized in an effective pattern via the reaction of diamines with isothiocyanates utilizing the ultrasonic irradiation as a sustainable energy source. This reaction performs well at mild conditions to give the products in quantitative yields for a broad scope of substrates. The bis-thiourea derivatives are used for the design of unprecedented series of bis-2-iminothiazolidin-4-ones promoted by the ultrasonic irradiation. The reaction affords the formation of regioselective products, which depends on the p K a s of the diamines. The diamine linked to the thiourea possessing lower p K a is involved in the imino part, and the diamine having higher p K a is a part of the other heterocyclic nitrogen. Moreover, this new strategy has excellent environmental parameters, demonstrating that this protocol is a green and sustainable process.