Functionalization of amines is a very important research area in organic chemistry because functionalized amines are important building blocks in many biologically active compounds and pharmaceuticals. Outlined within this dissertation are our efforts toward the development of redox-neutral amine functionalizations involving azomethine ylides. The redox-neutral approach avoids unnecessary manipulations on the oxidation state of a targeted molecular structure. Therefore it has many advantages over conventional methods in which metal catalysts, oxidants or other additives are required. We discovered the isomerization of the iminium ion via the intermediacy of azomethine ylides. We took advantage of this unique reactivity and successfully developed the redox-neutral cyanation of amines and intramolecular Mannich reactions. This redox-neutral Mannich reaction was further applied to the syntheses of natural product thalicatricavine and its unnatural epimer. Furthermore, we have conducted mechanistic studies of the redox-neutral aromatization of amines and provided experimental evidence for several important intermediates proposed for this transformation. The synthetic utilities of some of the intermediates were explored. Lastly, a novel intermolecular hydride transfer triggered functionalization of amines was also investigated.