Key words rhodium catalysis - C–H functionalization macrocyclic peptides tryptophan-containing

A new method for the covalent modification of poly­ mers in a two-step process is described. Squaric acid di­ ethylester reacts with primary or secondary aliphatic amines selectively to ester amides. It is shown for the first time that this class of compounds react with poly­ meric systems containing amine functionalities (e.g. g-amino groups of proteins) in aqueous solution, form­ ing stable s...

Compared to structurally related linear trialkylamines, a simple macrocyclic amine with an anion-binding cavity exhibits very large rate enhancements (>10(5)) for stoichiometric N-alkylation with primary alkyl, allyl, and benzyl halides in the weakly polar solvent CDCl3. There is also a major distortion of the halide leaving-group order. For example, with benzyl halides the relative leaving-gro...

Threading of a polymer through a macrocyclic ring may occur directly, that is, by finding the end of the polymer chain, or by a process in which the polymer chain first folds and then threads through the macrocyclic ring in a hairpin-like conformation. We present kinetic and thermodynamic studies on the threading of a macrocyclic porphyrin receptor (H2 1) onto molecular threads that are blocked...

Synthetic superoxide dismutase mimetics have emerged as a potential novel class of drugs for the treatment of oxidative stress related diseases. Among these agents, metal complexes with macrocyclic ligands constitute an important group. In this work we synthesized five macrocyclic copper(II) complexes and evaluated their ability to scavenge the superoxide anions generated by the xanthine-xanthi...

The membrane lipid of a new deep-sea hydrothermal vent methanogen, Methanococcus jannaschii, was isolated, purified, and structurally characterized. The total lipid extract, amounting to 32.2 micrograms/mg, dry cell weight, was fractionated on silica gel into a neutral lipid and polar lipid fraction. The neutral lipid fraction consisted of a series of isoprenoid hydrocarbons and free (nonphosph...

In this paper we report the synthesis and characterization of two new binuclear Cd(II) macrocyclic Schiff base complexes [CdL23pydfp(NO3)], (1), and [CdL33pydfp(NO3)], (2). [1+1] cyclocondensation of L23py = N-(2-pyridylmethyl)-N-(3-aminpropyl)-1,3-diaminoethane and L33py = N-(3-pyridylmethyl)-N-(3-aminpropyl)-1,3-diaminopropane and 2,6-diformyl-4-methylphenol, dfp, in the presence of Cd(NO3)2....

[reaction: see text]. The copper acetate mediated intramolecular O-arylation of phenols with phenylboronic acid pseudopeptides is the key step in the preparation of macrocyclic biphenyl ether hydroxamic acid inhibitors of collagenase 1 and gelatinases A and B. The intramolecular macrocyclization was found to be mild and tolerant of common chemical functionality. This methodology should provide ...