diethyl (1R,2S,E)-3-(2,2-dimethylpropylidene)cyclobutane-1,2-dicarboxylate

diethyl (1R,2S,3R)-3-(tert-butyl)-4-methylenecyclobutane-1,2-dicarboxylate

diethyl (1S,2R,3R)-3-(tert-butyl)-4-methylenecyclobutane-1,2-dicarboxylate

3-O-tert-butyl 1-O,2-O-diethyl propane-1,2,3-tricarboxylate

triethyl 3-methylbutane-1,2,3-tricarboxylate