Abstract:We have developed an effective approach to 1,2-disubstituted diamondoids by palladium(II) acetate catalyzed functionalization of C À H bond. Selective mono-arylation of the adamantane framework was achieved using picolylamide as a directing group in yields up to 87 %. Kinetic studies in combination with deuterium labeling experiments, competitive experiments and mass spectrometry contribute to the mechanistic understanding of the arylation process of alkanes with number of C À H bonds neighboring the directing group. Triflic anhydride promoted cyclization of the directing group generates imidazo[1,5-a]pyridine derivatives. Acid-mediated removal of the directing group provides access to 2-aryl diamondoid carboxylic acids, which are common precursors for the synthesis of various bioactive compounds (drug candidates).
Several analogues of vanchrobactin, a catechol siderophore isolated from the bacterial fish pathogen Vibrio anguillarum serotype O2 strain RV22, have been synthesized. The biological evaluation of these novel compounds showed that most of them are active as siderophores, as determined by growth promotion assays using the producer strain, as well as V. anguillarum serotype O1, Salmonella enterica, and Erwinia chrysanthemi. These compounds also gave a positive chrome azurol-S (CAS) test. On the basis of these results, we were able to deduce some structure-activity relationships. Furthermore, we found an analogue with siderophore activity that has appropriate functionality (an amino group) for use as an antibiotic vector to be employed in a "Trojan horse strategy".
We present a new approach to disubstituted diamondoids from corresponding carboxylic acids. A dirhodium‐acetate‐catalyzed (1 mol‐%) nitrene insertion reaction of sulfamides was, for the first time, applied to intramolecular C–H functionalization reactions of rigid tricyclic frameworks. This straightforward approach enables the effective and regioselective synthesis of a variety of diamondoid‐based cyclic sulfamidates, which are synthetically valuable building blocks. Reductive deprotection of the sulfamidate moiety leads to corresponding 1,3‐amino alcohol derivatives. Oxidation of the sulfamidate moiety by KMnO4 provides access to 1,3‐keto alcohols or imines. Finally, we report the synthesis of Vildagliptin® analogues as new antidiabetic drug candidates (DPP‐4 inhibitors).
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