Microwave-assisted scavenging of electrophiles utilizing polymer-supported sequestration reagents. Application to the synthesis of N3-acylated dihydropyrimidine libraries

Different scavenging techniques using polymer-supported sequestration agents are described for the purification steps in the synthesis of N3-acylated dihydropyrimidines. For scavenging both excess anhydride and unwanted byproducts, polystyrene and silica supported diamines, aminomethyl-functionalized SynPhase Lanterns and diethylenetriamine StratoSpheres Plugs are used. In both synthesis and purification microwave flash heating was utilized, reducing reaction times from hours to minutes. These two steps coupled with an efficient solid-phase extraction (SPE) workup allowed the generation of a 28-member library of N3-acylated dihydropyrimidines using anhydrides. Using related protocols a 15-member library of N3-functionalized dihydropyrimidines utilizing acid chlorides as acylating reagents was also obtained.