Synthesis Of Chiral Diphenylmethylpiperazine Compounds And Their Activities In Antiallergy

Allergy is a kind of excessive immune reaction. Allergic diseases are abroad in clinic . Besides , the incidence of the disease tends to increase recently . Among the therapies for it, H1 receptor antagonists (antihistamines) have shown to be effective clinically in the treatment of allergies . The classical antihistamines have some side effects such as restraining the central nervous system(CNS) and lasting shortly . Although the newer antihistamines have partly overcome the side effects of the classical antihistamines , some of them have other side effects such as the latent harm to the heart and vessel system . It is important to study and explore the newer antihistamines that have more significant effect and less side effect.Through investigation many antihistaminic drugs of piperazines, the diphenylmethylpiperazine skeleton is regarded as an essentially active part. Cetirizine is an excellent antihistaminic drug , bearing diphenylmethylpiperazine skeleton . Not long ago , it was found that levocetirizine displayed a better pharmacological profile than the racemic mixture . Little is known about the situation of other chiral diphenylmethylpiperazinederivatives . Therefore , we decided to synthesis some single enantiomers of them . Levorotatory and dextrorotatory enantiomers of cetirizine and other nine compounds were synthesized and were identified by MS, IR, 1H-NMR and elemental analysis .The activities of target compounds were evaluated in the antihistaminic experiment . The results showed that most of R-forms had better effect than the S-forms , and three of them had better effec than levocetirizine.