Oxygen heterocycles are one of the most common heterocycles in drugs and natural products. Oxetene has high polarity and is also a good acceptor for hydrogen bond, which contributes to the metabolism and chemical stability of its host molecules. When substituted for commonly used functional groups such as gem dimethyl or carbonyl, oxetane units can induce profound changes in water solubility, lipophilicity, metabolic stability and conformational preference. Four of the FDA-approved drugs contain oxetenes: Orlistat, Paclitaxel, and two of its derivatives, Docetaxel and Cabazitaxel. Currently, oxetane-containing building blocks are flourishing in medicinal chemistry and drug discovery.
When the ends of the chains are joined together into a ring, cyclic compounds result; such substances often are referred to as carbocyclic or alicyclic compounds. Substitution of one or more of the ring carbon atoms in the molecules of a carbocyclic compound with a heteroatom gives a heterocyclic compound.
Benzene is an important organic compound with the chemical formula C6H6, and its molecule consists of a ring of 6 carbon atoms, each with 1 hydrogen atom. Benzene is a sweet, flammable, colorless and transparent liquid with carcinogenic toxicity at room temperature, and has a strong aromatic odor. It is insoluble in water, easily soluble in organic solvents, and can also be used as an organic solvent itself. The ring system of benzene is called benzene ring, and the structure after removing one hydrogen atom from the benzene ring is called phenyl. Benzene is one of the most important basic organic chemical raw materials. Many important chemical intermediates can be derived from benzene through substitution reaction, addition reaction and benzene ring cleavage reaction.
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