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-We report the preparation of newly designed trivalent C 3 -symmetrical cyclic phenylboronic acid derivatives constructed on a symmetrical benzene or a cyclohexane ring. The synthesis of these C 3 -symmetrical molecules 4 was accomplished by an amide bond formation reaction using amino-substituted phenylboronic acid pinacol esters 2 and C 3 -symmetrical benzene-1,3,5-tricarboxylic acid trichloride 3a or cyclohexane-1,3,5-tricarboxylic acid trichloride 3b in the presence of Et 3 N. We confirmed that this procedure is conventionally applicable to the preparation of targeted C 3 -symmetrical cyclic boronic acid derivatives 4 in good to excellent yields. We also report the results of biological evaluation of the prepared compounds.Many host receptors that consist of homo-oligometric units (homo-multiligands) often construct symmetric macromolecule architectures such as C 2 -or C 3 -symmetrical geometry receptor systems.Molecular recognition of two-fold (C 2 ) or three-fold (C 3 ) geometric symmetrical macromolecules is one of the common features in several important biological processes. 1,2 With reference to the molecular symmetry, small oligovalent molecules having C 2 -or C 3 -symmetrical geometry have frequently appeared in various biologically active substances. [2][3][4] An oligovalent molecule is generally expected to show enhanced biological potential compared to that of the corresponding monovalent molecule. 4 On the other hand, regarding lectin-like carbohydrate recognition molecules, much attention has recently been paid to the design of synthetic receptors for carbohydrates. 5 We have been interested in small molecules that Figure 1). 9,10 From this point of view, we have recently synthesized a few 11 Figure 1As an extension of this study, we carried out further investigations of these symmetrical classes of compounds. In this paper, we report the synthesis of new trivalent C 3 -symmetrical phenylboronic acid derivatives incorporating a benzene or cyclohexane ring as a symmetrical template in the molecules and we report results of biological evaluations of the obtained C 3 -symmetrical phenylboronic acid derivatives.The results for synthesis of new C 3 -symmetrical cyclic boronic acid derivatives constructed on a benzene ring or a cyclohexane ring having three amide bonds are summarized in Tables 1 and 2. The synthesis of these target trivalent C 3 -symmetrical molecules 4aa~4ca constructed on a benzene ring was accomplished by an amide bond formation reaction using amino-substituted phenylboronic acid pinacol esters 2 and benzene-1,3,5-tricarboxylic acid trichloride 3a in the presence of a base such as Et 3 N. The preparation and physical and spectroscopic data of compounds 4aa~4ca have been reported in detail as a separated paper. 13 New C 3 -symmetrical compounds 4ab and 4bb constructed on a cyclohexane ring were also prepared by a procedure similar to that for compounds 4aa~4ca with cyclohexane-1,3,5-tricarboxylic acid trichloride in good yields (see EXPERIMENTAL). The structures of targe...

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