Using a convergent palladium-catalyzed construction of the carbazole framework as the key step we have achieved a short synthesis of the 7-oxygenated carbazole alkaloids clauszoline-K, 3-formyl-7-hydroxycarbazole, clausine C (clauszoline-L), clausine M, clausine N and the anti-HIV active siamenol.
A series of carbazole derivatives with promising pharmacological properties has been prepared using either an iron-mediated or a palladium-catalyzed synthetic approach. The carbazole alkaloids carbazoquinocin C, carbazomadurin A and B, epocarbazolin A and B, neocarazostatin B, and carquinostatin A are antioxidants acting as free-radical scavengers. Thus, they represent potential lead compounds for the development of novel drugs against diseases initiated by oxygenderived free radicals. Initiated by the first naturally occurring carbazole alkaloids with antituberculosis (anti-TB) activity, clausine K and micromeline, a study on the structure-activity relationships for anti-TB-active carbazole derivatives has been carried out. The 6-oxygenated carbazoles glycozoline and glycozolinine show antibiotic activity towards several microorganisms. The 7-oxygenated carbazole siamenol exhibits anti-HIV activity.
We describe the stereoselective transformation of diosgenin (4a) to (25R)-Delta(4)-dafachronic acid (1a),(25R)-Delta(7)-dafachronic acid (2a), and (25R)-cholestenoic acid (3a), which represent potential ligands forthe hormonal receptor DAF-12 in Caenorhabditis elegans. Key-steps of our synthetic approach are amodified Clemmensen reduction of diosgenin (4a) and a double bond shift from the 5,6- to the 7,8-position. In the 25R-series, the Delta(7)-dafachronic acid 2a exhibits the highest hormonal activity.
The interaction of Cu(II) with the following secondary N-substituted derivatives of di(2-picolyl)amine () are reported: N-cyclohexylmethyl-di(2-picolyl)amine (), N-benzyl-di(2-picolyl)amine (), N-(4-pyridylmethyl)-di(2-picolyl)amine (), N-(4-carboxymethylbenzyl)-di(2-picolyl)amine (), N-(9-anthracen-8-ylmethyl)-di(2-picolyl)amine (), 1,3-bis[di(2-picolyl)aminomethyl]benzene (), 1,4-bis[di(2-picolyl)aminomethyl]benzene () and 2,4,6-tris[di(2-picolyl)amino]triazine (). The solid complexes [Cu()(micro-Cl)](2)(PF(6))(2), [Cu()(micro-Cl)](2)(PF(6))(2).0.5CH(2)Cl(2), Cu()(ClO(4))(2), Cu()(2)(ClO(4))(2), [Cu()(ClO(4))(2)(H(2)O)].0.5H(2)O, Cu(2)()(ClO(4))(4), [Cu(2)()(Cl)(4)] and [Cu(2)(+H)(micro-OCH(3))(2)(H(2)O)](ClO(4))(3).C(4)H(10)O were isolated and X-ray structures of [Cu()(micro-Cl)](2)(PF(6))(2), [Cu()(micro-Cl)](2)(PF(6))(2).0.5CH(2)Cl(2,) [Cu()(2)(ClO(4))(2)(H(2)O)].0.5H(2)O, [Cu(2)()Cl(4)] and [Cu(2)(+H)(micro-OCH(3))(2)(H(2)O)](ClO(4))(3).C(4)H(10)O were obtained. The series is characterised by a varied range of coordination geometries and lattice architectures which in the case of [Cu()(ClO(4))(2)(H(2)O)].0.5H(2)O includes a chain-like structure formed by unusual intermolecular pi-interactions between metal bound perchlorate anions and the aromatic rings of adjacent anthracenyl groups. Variable temperature magnetic susceptibility measurements have been performed for [Cu()(micro-Cl)](2)(PF(6))(2) and [Cu()(micro-Cl)](2)(PF(6))(2).0.5H(2)O over the range 2-300 K. Both compounds show Curie-Weiss behaviour, with the data indicating weak antiferromagnetic interaction between the pairs of copper ions in each complex. Liquid-liquid (H(2)O/CHCl(3)) extraction experiments involving and as extractants showed that, relative to the parent (unsubstituted) dipic ligand , substitution at the secondary amine site in each case resulted in an increase in extraction efficiency towards Cu(II) (as its perchlorate salt); at least in part, this increase may be attributed to the enhanced lipophilicities of the N-substituted derivatives.
We present the synthesis and characterization of a family of partially protected block copolymers and their precursors synthesized by means of nitroxide mediated radical polymerization (NMRP) and a sequence of quantitative and orthogonal polymer analogous reactions. The target materials consist of an unprotected 4-hydroxystyrene block and a tert-butoxycarbonyl (BOC) or a tert-butyl (TBU) protected block. Corresponding precursor block copolymers exhibit low polydispersity indexes (PDI) (<1.36) and show well-defined compositions of their blocks. Techniques like NMR, FT-IR, GPC, DSC, and TGA were applied in order to verify structure, compositions, molar masses, molecular weight distributions, and thermal properties. These materials are promising candidates for self-assembly in thin films and subsequent photolithographic patterning applications.
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