For 10 points, name this functional group with two substituent groups singly bound to an oxygen.
This functional group is found in monensin and other ionophore antibiotics, which disrupt bacterial membrane transport by complexation with monovalent cations.  Those without significant bond strain generally show low reactivity, and are often used to (*) solvate organometallic reagents, but these compounds are also prone to autoperoxidation.  As six-member heterocycles, they are known as pyrans, and the five-member heterocycles are known as furans. The aryl type may be prepared using the Ullman condensation, which couples an aryl halide to a phenol in the presence of activated copper, while aliphatic ones may be be prepared from dehydration of alcohols or by nucleophilic substitution of an alkyl halide with an alkoxide ion, the Williamson synthesis.  For 10 points, name this functional group with two substituent groups singly bound to an oxygen.
This functional group is found in monensin and other ionophore antibiotics, which disrupt bacterial membrane transport by complexation with monovalent cations.  
{ether}s (1) [AU]