Cyrene™ blends: a greener solvent system for organic syntheses

Abstract

N,N-Dimethylformamide (DMF) and N-methylpyrrolidinone (NMP) are two of the common organic solvents which are facing increasing restrictions in terms of chemical safety and environmental regulations. Thus, seeking greener alternatives to replace them becomes an urgent need. Cyrene™ has recently evolved as one of the greener alternatives in many applications. However, its high viscosity greatly limits its broader applications. In this study, a series of Cyrene™ blends, a solvent system created by blending Cyrene™ with other common organic solvents, were developed and studied to address the Cyrene™'s viscosity issue. The material stability and applications in organic syntheses, i.e. HATU amide coupling, Suzuki coupling, Sonogashira coupling, N-alkylation, S_NAr reaction, aldimine reaction and 2-pyridyl homocoupling, are also investigated to demonstrate the usefulness of these Cyrene™ blends.