Synthesis and Physical-Chemical Properties of cis- and trans-1-Amino-3-fluoro-3-methylcyclobutanecarboxylic Acids
Eur. J. Org. Chem. 2016, 28, 4782-4786
Hitherto unknown cis- and trans-1-amino-3-fluoro-3-methylcyclobutanecarboxylic acids were synthesized as pure diastereomers starting from diisopropyl 3-oxocyclobutane-1,1-dicarboxylate. While pKa values of the carboxylic acid functions are the same for both stereoisomers (pKa = 2.80), the values for the amino groups are slightly different (8.46 or 8.77, respectively) presumably because of different interactions with the fluorine atoms.