3-dehydro-D-erythronate => 2-dehydro-D-erythronate
3-dehydro-d-erythronate => 2-dehydro-d-erythronate
3-dehydro-D-erythronate => 2-dehydro-D-erythronate
3-dehydro-d-erythronate => 2-dehydro-d-erythronate