MAC complex

Marshall and coworkers proposed the utilization of metal complexes of chiral azacrowns (MACs) as a strategy to influence the conformation of these macrocycles and to fix the chiral side chains in orientations comparable with those of peptidic p-tums [18-20]. For example, the MAC complex 3 was proposed to serve as... 

Until now, only a few effective ligands of this type have been identified (Fig. 25.4). Kagan and co-workers [5] prepared one of the few chiral diphosphines with only planar chirality and obtained 95% ee for the hydrogenation of DM IT with LI (Table 25.1, entry 1.1.), but enantioselectivities for several enamide derivatives were below 82% ee (the best results were with the cyclohexyl analogue of LI). For the reactions with DM IT or MAC, the cationic Rh-kephos complex showed comparable or better performance than corresponding duphos catalysts. 

Bppfoh and bppfa derivatives have been applied most successfully for the Rh-catalyzed hydrogenation of dehydro amino acid derivatives such as MAC (ee 97%) and of functionalized ketones [7]. The nature of the amino group has a significant effect on enantioselectivity and often also on activity, and is used to tailor the ligand for a particular substrate. Rh-bppfa complexes were among the first catalysts able to hydrogenate tetrasubstituted C=C bonds, albeit with relatively low activity (Table 25.2, entries 2.1-2.3). Ferrophos, one of the very few li-... 

Concerning the synthesis of graft copolymers, Jedlinski et al. have prepared poly(MMA-g-(3BL) copolymers via anionic grafting of 3BL from a modified PMMA backbone [85]. PMMA chains were partially saponified by potassium hydroxide and complexed by 18C6 crown ether so as to act as multifunctional mac-... 

Exchange-inert complexes of Cr(III) with nucleotide ligands are very stable toward hydrolysis. Such complexes have proven to be extremely useful as chirality probes in that different coordination isomers can be prepared and separated These nucleotide complexes have also proved useful as dead-end inhibitors of enzyme-catalyzed reactions. Because Cr(lII) is paramagnetic, distances can be measured by measuring the effects of Cr(lll) on the NMR signals of nearby atoms when the Cr(lll)-nucleotide complex binds to the surface of a mac-romolecule. See Exchange-Inert Complexes... 

Prevention of disseminated Mycobacterium avium complex (MAC) infections 1,200 mg taken once weekly. 

MAC Mycobacterium avium complex (typical bacterial infection in HIV or immunocompromised patients) maint maintenance MAO/MAOI monoamine... 

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