The molecules of this week are definitely recognized as morpholines! Not just morpholine derivatives, but rather constrained analogues with a geometric construction in the cycle. Why did we select them as "molecules of the week"? It is simple: morpholine is one of the most popular fragments in medicinal chemistry and is among TOP 30 most frequently used ring systems for small molecule drugs.[1] Morpholine has outstanding solubility and stability and these constrained analogues would definitely tune up activity and properties of your molecules!
[1] R. D. Taylor, M. Maccoss, A. D. G. Lawson, J. Med. Chem. 2014, 57, 5845–5859.