3-dehydro-L-erythronate => 2-dehydro-L-erythronate
3-dehydro-l-erythronate => 2-dehydro-l-erythronate
3-dehydro-L-erythronate => 2-dehydro-L-erythronate
3-dehydro-l-erythronate => 2-dehydro-l-erythronate