The molecular structure of cyclobutane has four carbon atoms, and its four carbon atoms are not in the same plane, which is the folded conformation of cyclobutane. Cyclobutane itself is not of commercial or biological interest, but more complex derivatives are important in biology and biotechnology. Currently, nine FDA-approved drugs contain the cyclobutane structure. From the perspective of therapeutic areas, cyclobutyl drugs are mainly distributed in popular areas such as tumors, neurological diseases, infectious diseases, endocrine and metabolic diseases.
Oxazolines are five-membered heterocyclic compounds with one double bond. The double bond may be in one of three positions, so there may be three different oxazoline rings. The 2-oxazoline structure is the most common, and 3-oxazoline and 4-oxazoline exist mainly as laboratory research compounds. Oxazolines exist between oxazole and oxazolidine in terms of saturation.