BINOL-derived phosphoramidite ligands

Several other groups developed alternative BINOL-derived phosphoramidite ligands for highly enantioselective copper-catalyzed Michael additions. Whereas Waldmann et al. included a bicyclic bispidine in... 

In 2012, Murakami et al reported the asymmetric intramolecular alkene insertion reaction of 3-(2-styryl)cyclobutanones catalysed by an in situ generated chiral nickel complex bearing a BINOL-derived phosphoramidite ligand 15 (Scheme 10.22). The reaction provided a unique and straightforward access to... 

BINOL-derived phosphoramidites are versatile ligands in palladium-catalysed umpol-ung allylation of aryl aldehydes mediated by diethylzinc.172 The possible roles of allyl-zinc and -palladium species in the mechanism are discussed in detail. 

As with other P(III) compounds, the binaphthol (BINOL) derivatives have been by far the most successful for a wide range of synthetic methods. Several reviews and reports have been published on the incorporation of BINOL-derived phosphoramidites in rhodium-catalysed asymmetric hydrogenations Novel chiral phosphine-phosphoramidite ligands, HY-Phos (61) and THNAPhos (62), have also been successful in rhodium-catalysed asymmetric hydrogenations. Asymmetric synthesis of the Roche ester and its derivatives (63) by rhodium-INDOLPHOS-catalysed hydrogenation was reported and a number of other BINOL-derivered phosphoramidates have been employed in iridium-catalysed hydrogenations and allylic alkyla-... 

Palladium-catalysed bisamidation of diene (116) has been attained with (117) as the reagent. Enantiomerically enriched product (118) was obtained (91% ee) in the presence of the axially chiral BINOL-derived phosphoramidites. DFT calculation revealed agostic interactions of the ligand with Pd (in addition to the normal chelation) and the C-W-n interaction between the diene and the aromatic system of the ligand these effects are believed to contribute to the stereoselctivity. ... 

The majority of the reported phosphoramidite ligands consist of BINOL and a diversity of readily available amines. Excellent enantioselectivities in the hydrogenation of a- and /fdehydroamirio acids, itaconates and enamides [63, 64] have been reported. In a recent full report, the group of Minnaard, De Vries and Fer-inga noted that especially the BINOL-derived ligands containing a piperidine or... 

Recently, Reek et al. published the synthesis of a 9H,9 H- [4,4 ]bicarbazole-3,3r-diol (BICOL)-based chiral monodentate phosphoramidite ligand, which was functionalized with two different third-generation carbosilane dendritic wedges (Fig. 26) [57]. As reference reaction in the catalytic study, the rhodium-catalyzed asymmetric hydrogenation of Z-methyl-a-acetamido-cinnamate was chosen. Using a ligand-to-rhodium ratio of 2.2 led to enantio-selectivities which were comparable to the results obtained using the parent BINOL-derived monodentate phosphoramidite MonoPhos. 

Many other binaphthalene-derived phosphoramidites were used as chiral ligands in copper-catalyzed Michael additions as well. Whereas 2,2 -bis(diphenylphosphino)-l,T-binaphthalene (BINAP) gave unsatisfactory stereoselectivities in Cu(OTf)2-catalyzed 1,4-additions of diethylzinc to enones,226 BINOL oxazoline phosphites obtained by Pfaltz et al. turned out to be remarkably versatile and in some cases complementary to phosphorami-... 

Hydrogenation. Phosphoramidite ligands to make up a Rh catalyst for enantioselec-tive hydrogenation of dehydroamino acid derivatives include 10, which is derived from 3,3 -bis(diphenylphosphino)-BINOL, and 11 that contains two binaphthyl groups. ... 

Hydrogenation Easily prepared monodentate phosphoramidite ligands containing a BINOL residue are employed in conjunction with (cod)2RhBp4 in asymmetric hydrogenation of dehydroamino acid derivatives and a-substituted acrylic esters (ee > 99% reachable). 

In spite of the prevailing application of homo- and heterobidentate chiral ligands, BINOL-derived monodentate phosphoramidites have been used in highly enantioselective rhodium-catalyzed hydrogenations (14,233). 

Besides the o-hydroxyphenyl amide (salicylamide) ligand used by the above workers, a plethora of other ligands such as phosphanes and diols (BINOL) have been used [77], and diketones, amino acids, 1,10-phenanthroline (phen) derivatives, oxalyldihydrazone, and phosphoramidite ligands have also been used [76]. 

In analogy with the Ir-catalyzed allylic alkylations described in the previous section, chiral phosphoramidite ligands derived from BINOL have shown excellent potential in copper-catalyzed asymmetric 8 2 substitutions [93], Alexakis recognized that ligand 86 in the presence of CuBr effects enantio-selective displacement with simple Grignard reagents (Scheme 14.16) [9]. Thus, the reaction between chloride 96 and MeMgBr in the presence of... 

Many other catalysts and ligands have been examined for the enantioselective reduction of a-acetamidoacrylates and related substrates. Phosphoramidites derived from BINOL and the cyclic amines piperidine and morpholine give excellent results.35... 

Considerable success has been realized for asymmetric hydrogenations of carbon-carbon unsaturation with monodentate ligands, especially those derived from BINOL. The most popular class is the phosphoramidites (157) as used by DSM.200 20 Phosphites (158) have also been successfully used in a wide range of asymmetric hydrogenations,202 as have phosphonites (159).203 204 These ligands are discussed in depth in Chapter 14. 

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