| 2-cyano-3-hydroxy-3-(1-methyl-2-piperidylidene)-acrylic aci ethyl ester |
| 2-((alpha-hydroxy-beta-carboethoxy-beta-cyanoethylene)imino)-1-methyl piperid |
| 2-cyano-3-hydroxy-3-(1-methyl-2-piperidylidene)acrylic acid ethyl ester |
| 2-cyano-3-hydroxy-3-((1-methyl-2-piperidinylidene)amino)-2-propenoic aci |
