The high and diverse biological activity of most alkaloids besides their few side effects has oriented the synthetic researches to develop new procedures for production of such natural products. For instance the African Calabar bean alkaloids, (-)-physovenine and (-)- physostigmine are widely used medicinally as cholinergic and miotics. It is useful in the treatment of glaucoma and myasthenia gravis and as antidote for organophosphate poisoning. Physostigmine can sufficiently improve the memory of the Alzheimer?s patients.

Hepatitis B virus (HBV) is the major cause of acute and chronic hepatitis which could lead to hepatocellular carcinoma. Currently, interferon- α and nucleosidic inhibitors of HBV reverse transcriptase, polymerase, lamivudine (3TC), adefovir and entecavir are the only drugs approved for the treatment of chronic HBV infection. However, interferon-α-produces many side affects with partial efficacy less than 30% of the chronic carriers responding to treatment.

Click Chemistry ‘CC’ are Cu(I) catalyzed 1,3-dipolar [3+2] cycloaddition between azides and alkynes [CuAAC]. The versatility of CuAAC or ‘click reaction’ seem endless with the discovery and invention of new chemical transformations which meet ‘click’ status, the future looks bright for CC. Recently, Click chemistry has received considerable attention as powerful modular synthesis approach, which has found numerous applications in many areas of modern organic chemistry, drug discovery, radiopharmaceutical sciences and material science.