A Simple Method of Synthesis of (+-)-2,3-Diarylpiperazines and a Novel Method of Resolution of (+-)-2,3-Diphenylpiperazine

摘要

Intramolecular reductive coupling of diimines in the presence of Zn/Ti(O~iPr)_2Cl_2 gives the corresponding (+-)-2,3-dia-rylpiperazines in 73-83% yields with dllmeso ratio >99%:<1%.The (+-)-2,3-diphenylpiperazine obtained in this way was readily resolved partially using L-(+)-tartaric acid,and the enantiomeric purity was enhanced to >99% ee via preparation of hydrogen-bonded salt aggregates using oxalic acid.