Structures of the R-etomidate (R-ethyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate), S-etomidate (S-ethyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate), cyclopropyl etomidate (ethyl 1-(1-phenylcyclopropyl)-1H-imidazole-5-carboxylate), and dihydrogen etomidate (ethyl 1-benzyl-1H-imidazole-5-carboxylate). The chiral centers in the two etomidate enantiomers are indicated by asterisks.