Tripodal amine

Me has described the use of an optically active tripodal amine, (25, 65)-2,6-bis(o-hydroxyphenyl)-l-(2-pyridyhnethyl)piperidine (68) as a potent catalyst for methano-lytic ASD of cyclic mei o-anhydrides (Fig. 16) [227], This catalyst was envisaged to adopt a helical conformation thereby providing a highly asymmetric environment for the nucleophihc teri-amine lone pair whilst also allowing activation of the anhydride substrate by the phenolic hydroxyl groups. In the event, ees up to 81% were obtained for the methanolytic ASD of a cyclic meio-anhydride when employed at the 5 mol% level for 20 h at 0 °C in toluene [227]. 

The first of two conversions catalyzed by the metalloenzyme tyrosinase is the selective ortho-hydroxylation of a phenol moiety, yielding catechol. Few synthetic systems exist that are capable of selectively performing the same monooxygenase reaction [172-178]. The group of Casella has studied a series of dicopper complexes based on 2,6-disubstituted benzene hgands providing two N3 compartments [179-181] (26a,b) as well as the asymmetrically substituted tripodal amine-based ligand (27) [182]. 

During a study in which the cyclic tripod amine Af,Af, Af"-trimethyltriazacyclononane (TAEN) was used as a solvent for Me2Mg, a rather unexpected product was obtained... 

Si-Si coupling and Si-X functionalization had to be modified and extended. The preparation of CH3Si[Si(CH3)3]3 is based on the procedure reported by Marsmann et al.6 The functionalization of the branched-chain silane occurs by the method introduced by Ishikawa et al.7,8 and leads to the desired trichloro-derivative,9 which can easily be converted to a tripodal amine by aminolysis with a primary amine.5... 

Even simple protonated tripodal amines such as tren (2,2, 2,-tr/s(aminoethyl)amine, 4.6) itself exhibit interesting anion-binding geometries. The X-ray crystal structure of tren-HBr (Figure 4.11a) shows the bromide anion interacting with all three terminal amine groups, one of which is protonated.16... 

Hossain, M. A. Liljegren, J. A. Powell, D. Bowman-James, K. Anion binding with a tripodal amine,... 

Variable-temperature ll-. 13C- and z9Si-NMR spectroscopy was used in an investigation of the reversible transformation of the tripodal amine 61 to azadisilacyclobutane 62. The NMR spectra showed that at 295 K in a solution of toluene-rfg, the equilibrium between 61 and 62 lies almost entirely on the side of the tripodal amine. When the temperature of the solution rose to 355 K, the equilibrium almost completely shifted toward azadisilacyclobutane 62 and the free amine (Scheme 2). However, the compound 62 was not isolated in pure form <2001CEJ2563>. 

Attempts to synthesize the clathrochelate complexes of lanthanide ions via template condensation of the tripodal amine tren with formaldehyde bis-(dimethylamino)methane derivative on the rare-earth metal ion were successful only for ytterbium. The [Yb(metr)](CF3S03)3 AN clathrochelate was obtained in 3-5% yield [165]. With ytterbium cation, as well as with cerium, praseodymium, europium, yttrium, and lanthanum ions, the major reaction products proved to be mono- and dibridged semiclathrochelate complexes with ligands 1 and 2 (Scheme 71). 

The template condensation of tripodal amines or carbonyls with ketoximes and aminoximes, respectively, in the presence of alkaline-earth metal ions is assumed to be the most obvious pathway for the synthesis of semiclathrochelate oxime-containing ligands capable of coordinating transition metal ions followed by capping with Lewis acids (Scheme 139). 

Adamantanetriontrioxime may be regarded as an analog of tripodal amines in the synthesis of macrobicyclic Schiff bases and is promising in the formation of rigid clathrochelates with expanded cavity (Scheme 146). 

Fig. 26) (230). This led to a Mn11 complex having a square prismatic geometry. The second complex is composed of a cryptate ligand that yields a complex with a cubic symmetry (Fig. 27) (231). The third structure is built up from two tetradentate tripodal amine ligands about the Mn I ions (Fig. 26) (232). 

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