Solvent-free, two-step synthesis of some unsymmetrical 4-aryl-1,4-dihydropyridines

4-Aryl-1,4-dihydropyridines are efficiently synthesised under solvent-free conditions in high yield. The use of volatile solvents is restricted to recrystallisation of the product, which, due to the high degree of conversion, is kept to a minimum. Optimisation of reaction conditions by careful consideration of the reaction rate and extent of conversion is demonstrated. This is yet another example of how readily solvent-free reactions may be implemented in the highly reproducible and efficient preparation of pure therapeutic agents with minimal production of waste and optimised use of energy.