3,3-difluoro-1-[(2-methylpropan-2-yl)oxycarbonylamino]cyclobutane-1-carboxylic acid

tert-butyl N-[3,3-difluoro-1-(hydroxymethyl)cyclobutyl]carbamate

3-hydroxycyclobutane-1,1-dicarboxylic acid

diethyl 3,3-difluorocyclobutane-1,1-dicarboxylate

diethyl 3-fluorocyclobutane-1,1-dicarboxylate