A synthetic strategy for dendrimers was developed using Staudinger/aza-Wittig reaction with an aldehyde and an azide in the presence of triphenylphosphine, followed by the reduction of imine intermediates. A fusion method between Fr$acute{e}$chet-type dendritic benzaldehydes and F$acute{e}$chet-type dendritic benzyl azides led to the formation of first-through fourth-generation dendrimers containing secondary amine as a connector in high yields. Further, fusion coupling using different generation dendrons afforded, efficiently, the unsymmetrical dendrimers. The obtained dendrimers were characterized by the analyses of $^1H$ and $^{13}C$ NMR spectroscopy, IR spectroscopy, mass spectra, and gel permeation chromatography (GPC) analysis.