Polymer-supported stereoselective synthesis of benzimidazolinopiperazinones.

We describe the efficient synthesis of 4,7,8,10-tetrasubstituted-(((4S,10aS)-3-oxo-3,4,10,10a-tetrahydrobenzo[4,5]imidazo[1,2-a]pyrazin-2(1H)-yl)alkyl)amides on solid phase via tandem N-acyliminium ion cyclization-nucleophilic addition reactions. The synthesis proceeded with complete stereocontrol of a newly formed stereogenic center, provided crude material of high purity, and used commercially available building blocks under mild reaction conditions.