Amidophosphine

Several efficient amidophosphine- and aminophosphine-phosphinite ligands have been reported by Agbossou and Carpentier.148,148a 148g Amidophosphine-phosphinite ligands (.9)-Cy.Cy-oxoProNOP and (.V)-Cp,Cp-oxoProNOP... 

Use of ferrocenylmonophosphine (fU-(A)-PPFA 5a for the same reaction improved the enantioselectivity.24,25,26 Here, the hydrosilylation product was oxidized into ( y)-l-phenylethanol 3 with 52% ee (entry 3). The ferrocenylmonophosphine 6 supported on Merrifield polystyrene resin has been also used for the hydrosilylation of styrene, though the enantioselectivity was lower (15% ee) (entry 4).27 Several chiral (/ -/V-sulfonylaminoalkyl)phosphines 7 were prepared from (A)-valinol and used for the asymmetric hydrosilylation of styrene.28 For styrene, phosphine 7a which contains methanesulfonyl group was most effective giving (asymmetric hydrosilylation (entries 6-9).29,29a... 

BPPM Scheme 1.17) was used as catalyst [60]. The enantioselective hydrogenation of functionalized ketones was also efficiently achieved by a series of rhodium(I) aminophosphine- and amidophosphine-phosphinite complexes [61]. 

The asymmetric hydrogenation of enol esters can also be catalyzed by chiral amidophosphine phosphinite catalysts derived from chiral amino acids, but the enantioselectivity of these reactions has thus far been only moderate.35... 

Lithiation of the dicarboxamide 365 is similarly diastereoselective, and after two successive n-BuLi-(—)-sparteine lithiations C2-symmetric products such as 367 can be made with high ee (Scheme 156) Attempted double lithiation of 365 in one pot fails with n-BuLi with s-BuLi-(—)-sparteine the major product is the meso isomer of 367 ". The amidophosphine 366 has been used as a chiral ligand for Pd chemistry the amides can be reduced to amino groups with BHsiTHF . 

When we entered the field, Tomioka et al. had just introduced the dialkylzinc addition to N-sulfonylimines in the presence of chiral amidophosphine-copper(II) complexes, producing high levels of enantioselectivity (up to 94% ee) [27]. At the... 

Amido phosphine-donor complexes, with Zr(IV), 4, 799 Amidophosphines, chelating, in hydrogenations, 10, 14 Amido-supporting ligands... 

Leautey, M. Castelot-Deliencourt, G. Jubault, P. Pannecoucke, X. Quirion, J.-C. Synthesis of a-substituted /i-amidophosphines by diastereoselective alkylation. A new access to chiral ligands for asymmetric catalysis. 

Addition of dialkylzinc reagents to /3-aryl- and /3-alkyl-nitroalkcncs, RCH=CHN02, catalysed by a complex of (TfO)2Cu with the proline-derived amidophosphine (193), afforded the corresponding nitroalkanes with moderate to good enantioselectivities (54-80% ee). The performance was highly dependent on the reaction procedure thus,... 

A C2 symmetric bis(amidophosphine) ligand was used by Trost to prepare the natural nucleoside adenosine (see Chapter 49 for nucleosides) in similar fashion to the carbocyclic analogue described above. The key enantioselective step was the first allylic alkylation that selected between two cnan-tiotopic benzoates in the meso dihydrofuran derivative to give one enantiomer the expected cis product. 

As final examples of potentially P,0 bitopic ligands, amidophosphines have been applied with success to various enantioselective transformations, e. g., addition of arylboronic acids, Grignard reagents, and organocuprates to enones in the presence of Rh and Cu catalysts (10) (>96% ee) [40]. 

Based on the metal-differentiating coordination concept, proline-derived biden-tate amidophosphines 23-25 were developed. The carbonyl oxygen and phosphorus atoms of the ligand selectively coordinate to lithium and copper atoms of an organocopper species, which discriminate the reaction face of the complex as shown in 26. The reaction of dimethylcopper lithium with chalcone gave the adduct in 84% ee [52]. Enantioselectivity was later improved to 90% with the more bulky amidophosphine 25 based on the model 26 (Eq. (12.26)) [53]. 

Catalytic asymmetric reaction was realized by using 8 mol% of copper iodide and 32 mol% of the chiral amidophosphine 24 to afford the /(-substituted cycloalkanones... 

Owing to strategic reasons, Lonza exited the dextrometorphan business before the process could be transferred. Subsequently a further study of the hydrogenation of 10, using iridium complexes with chiral amidophosphine-phosphonite ligands, was published by another group [14]. An enantioselectivity of 86% ee was reached, but the chemoselectivity was low. 

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