The copper(I) complex [Cu(C18(6)tren)]Br 1 (C18(6)tren = tris(2-dioctadecylaminoethyl)amine) which exhibits a good stability towards aerobic conditions is a versatile, highly reactive and recyclable catalyst for the Huisgen cycloaddition of azides with terminal or internal alkynes and is a useful catalyst for the preparation of "click" dendrimers.

The tetramine ligand 1 hexasubstituted by very long alkyl chains (C18H37) exhibits an exceptionally large temperature-dependent solubility in 1,4-dioxane, its solubility increasing ca. approximately 104-fold between 23 and 50 degrees C. The preformed copper(I) complex CuBr/1 was shown to catalyze the atom transfer radical polymerization of methyl methacrylate with good control of the molar masses and polydispersities. Due to the thermoresponsive character of CuBr/1 polymerizations were carried out in homogeneous conditions while lowering the temperature to 10 degrees C led to the precipitation of the catalyst. Catalyst recovery was achieved with high yield ( approximately 95%) by a simple filtration under noninert atmosphere. Very low residual copper contamination ( approximately 200 ppm) was measured in the final polymer. The catalyst was recycled two times without significant loss of activity.

The concept of a "fluoro biphasic system" (FBS) has been introduced recently by Horvá th and Rabái. 1 In this approach, the catalyst is confined to the fluorocarbon phase whereas the substrate and the reaction products are dissolved in an organic solvent. The system is biphasic at low temperature and becomes homogeneous at a higher temperature. The major advantages of the FBS is the very simple workup since the reaction products remain in the organic phase, allowing easy recovery of the catalyst for another reaction sequence. Moreover, due to their chemical inertness, perfluorinated compounds are environmentally friendly. This approach has been applied for many organic reactions such as organotin hydride reduction, 2 Stille coupling reaction, 3 or addition of allyl tin derivatives onto aldehydes. 4 Oxidation reaction catalysts such as ruthenium or nickel complexes, 5 manganese, 6 and cobalt or copper complexes 7 as well as a hydroformylation catalyst 8 or the fluorinated analogue of Vaska's complex 9 have been prepared with ligands bearing perfluoroalkyl side chains.In this paper, we report an efficient FBS-based catalysis for atom transfer radical additions (ATRA). This technique uses a low valent metal to induce the radical cleavage of a carbon-halogen bond. The metal-bonded radical can react in a radical-like process. As the transition metal mediated cleavage of the carbon-halogen bond is reversible, the reacted radical gives a new halogenated product by reductive elimination and allows the recovery of the catalyst at the end of the reaction. 10 This concept has been developed extensively by Speckamp and coworkers to perform copper(I)-catalyzed radical cyclization of unsaturated trichloro ester. 11 The major drawback of these reactions is the large amount of metal complex (ca. 30 mol %) required in order to complete the reaction. We recently reported the preparation of copper(I) and iron-(II) complexes that allow high reaction turnovers even with a very low catalyst/substrate ratio (3 mol %). 12 In this note, we describe the synthesis of two perfluoroalkylated polyamines as potential ligands for copper or other transition metals. The copper complexes associated with a reducing agent (iron powder) allow the radical cyclization of an unsaturated trichloro ester in high yield using the FBS procedure with an efficient recovery of the catalyst.The required perfluorinated ligands, the tri and tetradentate ligands 4 and 5 are prepared by standard techniques for introduction of perfluoroalkyl chains. 6,13 A three methylene carbon spacer is also introduced in order to insulate the amine from the strong electronwithdrawing effect of the perfluoroalkyl group. This procedure has been already described and involves the radical addition of perfluorooctyl iodide to allyl alcohol to provide the iodo alcohol 1 (Scheme 1). Reduction of compound 1 by tributyltin hydride afforded 2 in 88% yield. Subsequent tosylation of compound 2 provided the key material 3 for the peralkylation reaction of diethylenetetramine and tris(amino...