Modular ligand

SHRs are built in a modular structure with similar structure elements. They contain a DNA-binding domain (DBD), a hinge region with a nuclear location signal (NLS), a ligand-binding domain (LBD) and several transcriptional activation functions (Fig. 1). 

Figure 4.1 clearly illustrates the modular construction of MOFs, with ligands used as pillars and metal clusters as node points. One unique feature of MOFs seems to be the possibihty to systematically modify their lattice. For instance, by replacing the terephthalate ligands of MOF-5 (Figure 4.1) with different dicarboxylate ligands, a family of isoreticular metal-organic frameworks (known in literature as the... 

In 2008, Gade and coworkers reported that the asymmetric hydrosilylation of ketones was catalyzed by the Fe complex with a highly modular class of pincer-type ligand (Scheme 22) [71]. This Fe catalyst system showed both moderate to good... 

Along these lines, imidazoline [68, 69] rather than oxazoline coordination sites better fitted into a modular concept in order to understand how the electronic properties should ideally be, since electron density can be readily adjusted by the choice of the N substituent [70]. The Cp ligand C5R5 in 47 permits steric and electronic tuning. With the electron-withdrawing effect of five Ph groups R, the... 

Since carbohydrates constitute an inexpensive and highly modular chiral source for preparing chiral ligands," Claver et al. have reported the use of a series of thioether-phosphite" and thioether-phosphinite furanoside ligands" in the test palladium-catalysed allylic substitution reaction. In the first type of ligand, a systematic variation of the donor group attached to the carbon atom C5 indicated that the presence of a bulky phosphite functionality had a positive effect on the enantioselectivity. Indeed, the enantioselectivity was controlled mainly by the phosphite moiety. This was confirmed by the use of a ligand... 

There are certain catalyst systems which appear to be more amenable to combinatorial studies than others. For example, libraries of small peptides as ligands are particularly easy to prepare (e.g., on solid supports), and due to their modular nature high diversity is possible. High diversity is also readily achieved when using mixtures of two or more chiral monodentate ligands.122 This novel approach offers many perspectives. 

A remarkable number of chiral phosphorus ligands (phosphoramidites, phosphites, and phosphines with modular structures) have been introduced into the copper-catalyzed conjugate addition of R2Zn reagents, and high enantio-selectivities (>90%) are now possible for all three different classes of substrates 2-cyclohexenones and larger ring enones, 2-cyclopentenones, and acyclic enones. 

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