顺式-1,2,3,4-环戊烷四羧酸

草酸

endo,endo-5,6-dihydroxybicyclo[2.2.1]heptane-endo,endo-2,3-dicarboxylic acid dilactone

对甲苯磺酸

降冰片烯-2,3-二羧酸