synthesized by the Pictet-Spengler reaction. Influence of a wide range of aryl and heteroaryl aldehydes, was investigated in the cyclization step with 3,4-dimethoxyphenylethylamine 1, L-DOPA 2 and L-3,4-dimethoxyphenylalanine methyl ester 3. Compounds 2 and 3 served as probes to assess the efficiency of two Pictet-Spengler reactions with respect to their diastereoselectivity, in order to obtain optically