The stereoselective addition of aryl- and alkylacetylene derivatives to imines was studied. The reaction is catalyzed by copper complexes of enantiomerically pure bisimines, readily prepared in very high yields from the commercially available binaphthyl diamine. A very simple experimental procedure allowed to obtain at room temperature optically active propargylamines in high yields and enantioselectivity. Interestingly, bisimine/copper(I) complexes were able to promote the direct, enantioselective, catalytic addition to imines of alkylacetylenes. The effects of catalyst loading and other reaction parameters on the stereochemical outcome of the transformation were investigated. The extremely convenient methodology, the mild reaction conditions, and the possibility of a modular approach for developing new and more efficient bisimine-based chiral ligands make the present methodology very attractive.

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New enantiomerically pure macrocycles have been prepared by combining 1,10-phenanthroline 2,9-dicarboxylic acid and two a-amino-acids linked through spacers. Different diamine linkers have been employed in order to modify the dimensions and the properties of the macrocycles whose structures have been studied by 1 H and 13 C NMR spectroscopy. The ability of the (L)-valine containing macrocycles to bind metal ions and phenolic molecules has been investigated by 1 KEY WORDS: chiral macrocycles; asymmetric catalysis; phenanthroline; molecular recognition; molecular modelingThe synthesis of new chiral multifunctional macrocyclic structures is a fascinating topic that finds application in different areas. The design of receptors containing multiple recognition sites has recently attracted considerable attention in the field of molecular recognition. 1 Multifunctional macrocycles have also attracted attention as ligands for the preparation of lanthanide complexes with interesting luminescence properties and have been employed in biological applications. 2 The construction of receptor molecules containing a metal coordinating element leads to synthetic molecules that mimic key features of enzyme activity. 3 The design of such artificial enzymes, where a transition metal is placed within the framework of a chiral macrocycle, can have applications in asymmetric catalysis. 4 The combination of a metal-chelating unit and chiral subunits held in a macrocycle through linkers is particularly attractive, since it offers the possibility of locating the catalytically-active site in a chiral environment. 5 We have recently reported the preparation of enantiomerically pure bipyridine and phenanthroline-based macrocycles that have been successfully used as chiral ligands in the asymmetric cyclopropanation promoted by copper (I) triflate complex. 6 Three elements were combined in building the new catalytic system: a chiral auxiliary, a nitrogen-containing ligand site, and a connecting unit that may offer further points of diversity by modification of the size and nature of the chemical bonds linking the different units of the assembly (model-structure A in Fig. 1).Following our interest in developing enantiomerically pure phenanthroline-containing macrocycles, we have connected the phenanthroline unit to chiral residues derived from amino acids. 7 The use of diamine linkers with different length and flexibility should allow the modulation of the size and shape of the macrocycle cavity (model-structure B in Fig. 1). Besides potential use as chiral ligands in asymmetric catalysis, the new structures feature different hydrogen bond donors and acceptors that make them potential candidates in multisite molecular recognition phenomena.We report here the synthesis of such new enantiomerically pure macrocycles, their structure determination via NMR techniques, and preliminary studies of their behaviour as catalysts and in hydrogen-bond-based recognition phenomena. MATERIALS AND METHODS General MethodsMelting points are uncorrected...

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