Nonlinear effects in proline–thiourea host–guest complex catalyzed aldol reactions in nonpolar solvents

Abstract

An aldol reaction catalyzed by a proline–thiourea host–guest complex in a nonpolar solvent shows excellent nonlinear effects. This proline–thiourea system has the ability to form a hydrogen-bonding network. The enantiomeric excess of proline in a solution can be significantly enhanced by its incorporation with a urea molecule into its solid racemate. This suggests a general and facile route to homochirality, which may be involved in the origin of chirality on earth.