Combined methods of cyclophane and bipyridine synthesis open the way to the new planar-chiral 2,2'-bipyridine 1, whose CD spectrum is strongly dependent on metal salts. The absolute configuration of the chiral precursor 2 could be assigned by comparison of experimental and theoretical CD spectra. The usefulness of planar chirality in heterocyclic transition metal ligands is revealed in experiments towards stereoselective catalysis using 1.Chiral ligands are the key compounds in asymmetric catalysis. 2 A ligand playing a major role in transition metal complexation is 2,2'-bipyridine, which has been frequently provided with stereogenic centres. Chiral bipyridines are not only used in asymmetric synthesis, 3 but also for the organization of stereochemically defined supramolecular 4 structures. 5 We combined intramolecularly two structural features that have always been important in stereochemistry as well as in coordination chemistry, the [2.2]paracyclophane system and the 2,2'-bipyridine complex ligand, resulting in a planar chiral ligand of a new type, 13-pyridinyl [2](1,4)benzeno[2](2,5)pyridinophane (1).The number of planar chiral ligands based on ferrocenes in catalytic asymmetric synthesis is very high. 6 A [2.2]paracyclophane skeleton, however, has rarely been described so far in this field. 7 We now make use of the special attributes of the [2.2]paracyclophane type scaffold as chiral unit. It possesses a high sterical demand that is particularly effective because of its rigidity. Furthermore, the chiral information is located near to the metal ion, one side being shielded by the benzene ring.To obtain the key educt for 1, the [2](1,4)benzeno[2](2,5)pyridinophane (2), which is once mentioned in literature, but, concerning synthesis and precursors, was insufficiently described, 8 we proceeded from commercially available 2,5-pyridinedicarboxylic acid, which was converted into the diethyl ester via the acid chloride.The diol 3, generated by reduction of the ester through sodium borohydride/calcium chloride in ethanol, 9,10 could be isolated exclusively by using a strongly acidic cation exchange resin (e.g. Amberlite IR 200 C) 11 . After bromination of the diol, 12 we obtained the dibromide 4. Under high-dilution conditions 13 and by taking advantage of the cesium effect, 14 4 was coupled with 1,4-bis(sulfanylmethyl)benzene to yield 2,11-dithia [3](1,4)benzeno[3](2,5)pyridinophane 5.Irradiation of 5 with ultraviolet light (Hg, 180 W) in a thiophilic solvent generated the [2.2]phane 2, the N-oxide Reagents and conditions: i, SOCl 2 , reflux, 8 h, recryst. of acid chloride (petroleum ether 40/60), then EtOH, reflux, 2 h, 82%; ii, NaBH 4 (2 equiv), CaCl 2 (1 equiv), EtOH, r.t., 16 h, 67%; iii, HBr/HOAc (30%), r.t., 6d; iv, sol. A: 4 in EtOH, sol. B: 1,4-bis(sulfanylmethyl)benzene (1 equiv), KOt-Bu (2.3 equiv) in EtOH (85%); Cs 2 CO 3 in mixture, reflux, 16 h, 62%; v, P(OMe) 3 , hν (Hg, 180 W), r.t., 18 h, 84%; vi, MCPBA (2 equiv), CH 2 Cl 2 , r.t., 20h, then N,Ndimethylcarbamoyl chloride (1.3 equiv.), TMSCN (1.3 equ...

New chiral dendrimers with planar-chiral, cycloenantiomeric and topologically chiral cores were prepared in yields of up to 90% starting from a racemic 4-hydroxy[2.2]paracyclophane, a [2]rotaxane with sulfonamide groups in the wheel and axle positions and [2]catenane with a sulfonamide group in both of its macrocycles. The separation of the racemic mix-

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Monofunctionalized Dendrons of Different Generations – as Reagents for the Introduction of Dendritic Substituents In recent years dendrimers become more and more important not only in organic chemistry. They represent a new class of molecules with unique characteristic features. But dendrimers represent not only designed molecular architecture. They stand for a new concept in chemistry. They can be used to alter the properties of already existing molecular skeletons or they can be used to transfer new properties to a classical functional unit. This means that functionalized dendrimers and dendrons (dendritic building blocks) can be regarded as reagents for the preparation of new compounds with dendritic properties. In this article the synthesis and the practical use of appropriate dendritic reagents is explained. Furthermore we introduce the new technical terms „{n} dendryl‐”︁ for dendritic substituents of n generations and „dendriagent”︁ which stands for dendritic reagents. Moreover we give a short outlook on future developments.

445In recent years, homogeneous asymmetric catalysis with metal complexes has been a very fast developing field of research [1]. Most of the organic reactions in which prostereogenic compounds can be used, are now feasible under metal-complex-catalysis. The ligands used in these reactions, for the most part, possess phosphorous donor groups as coordination sites. Nitrogen ligands, not as numerous as their phosphorous counterparts, find more and more interest in the last few years, too [2]. Planar chirality generated by making use of the unique [2.2]paracyclophane skeleton, however, is very rare both in the field of phosphorous and nitrogen ligands [3]. Recently, we reported the synthesis and enantiomeric resolution of the first planar chiral 2,2'-bipyridine with [2.2]paracyclophane skeleton (8) and its use in asymmetric catalytic reactions [4].To find out more about the opportunities, which this new lead structure for the design of chiral ligands offers, we now synthesized pyrid-2-yl With this key-compound in hand, we could synthesize the hitherto unknown title compound 1 in a one-stepprocedure, by cobalt-catalyzed cyclisation with acetylene (Bönnemann-reaction) [8].recorded. The enantiomerically pure title compound 1 is used in copper-catalyzed asymmetric cyclopropanation of styrene and in asymmetric iridium-catalyzed transfer-hydrogenation of acetophenone.The synthesis of 1 proceeded via the NBS-bromination of 5,8-dimethylquinoline [6] (3) leading to the dibromide 4. Cyclisation of 4 under high-dilution conditions with 1,4-bis(mercaptomethyl)benzene generated the new dithiaphane 5, which was irradiated by UV (Hg, 180 W) in a thiophilic solvent (P(OMe) 3 ). By cyana-