A series of 4-dihydroxyborylphenyl analogues of an unnatural α-amino acid, 1- aminocyclobutanecarboxylic acid (ACBC), was synthesized. Varying numbers of methylene units were introduced between the 4-boronophenyl and ACBC moieties in order to introduce different degrees of lipophilicity into the molecules. The key step in the syntheses was the preparation of the precursor p-boronophenyl-substituted cyclobutanones which were ...