Piperidines and their derivatives have become increasingly popular building blocks in a vast array of synthetic protocols. The piperidine ring, a six-membered ring containing one nitrogen atom, can be recognized not only in the structure of more than half of the alkaloids known today, but also in many natural or synthetic compounds with interesting biological activities. 1-Boc-2-(aminomethyl)piperidine has been used in a post-Ugi carbonylation/intramolecular amidation approach to a series of eight-membered macrolactams with multiple points of diversity. Additionally, the unprotected analogue has been employed in the synthesis of melanocortin 4 receptor antagonists. These antagonists are potentially useful in the therapeutic treatment of involuntary weight loss. Fluorinated piperidines are also the subject of continued interest in medicinal chemistry, such as in the synthesis of selective dipeptidyl peptidase II (DPP II) inhibitors.