Ethyl 3a,4,6,6a-tetrahydrofuro[3,4-d][1,2]oxazole-3-carboxylate

5,6,7,8-tetrahydro-4H-cyclohepta[d][1,2]oxazole-3-carboxylic acid

5-(氯甲基)-3-异噁唑羧酸乙酯

异噁唑-3-羧酸

diethyl 1,2,5-oxadiazole-3,4-dicarboxylate 2-oxide