A simple method of synthesis of (+/-)-2,3-diarylpiperazines and a novel method of resolution of (+/-)-2,3-diphenylpiperazine.
Intramolecular reductive coupling of diimines in the presence of Zn/Ti(O(i)Pr)2Cl2 gives the corresponding (+/-)-2,3-diarylpiperazines in 73-83% yields with dl/meso 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.
Vairaprakash
Pothiappan
P
School of Chemistry, University of Hyderabad, Central University P.O., Hyderabad 500 046, India.
Periasamy
Mariappan
M
D001713:Biphenyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010084:Oxidation-Reduction; D010879:Piperazines / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
D001713:Biphenyl Compounds; D010879:Piperazines