Monophosphoramidite

Feringa and co-workers applied monophosphoramidite ligand 81 in the addition of phenylboronic acid to nitroalkene and got moderate enantioselectivity (Scheme 39).118... 

It thus came as a surprise that in the year 2000, three groups independently reported the use of three new classes of monodentate ligands (Scheme 28.2) [12], The ligands induced remarkably high enantioselectivities, comparable to those obtained using the best bidentate phosphines, in the rhodium-catalyzed enantioselective alkene hydrogenation. All three being based on a BINOL backbone, and devoid of chirality on phosphorus, these monophosphonites [13], monophosphites [14] and monophosphoramidites [15] are very easy to prepare and are equipped with a variable alkyl, alkoxy, or amine functionality, respectively. 

Breakthroughs that took place around the year 2000 have shown, in contrast to the common view, that indeed chiral monodentate phosphorus ligands can also lead to high enantioselectivities in a number of asymmetric hydrogenations. In the years following, monophosphines, monophos-phonites, monophosphoramidites, and monophosphites have been successfully used in the enantioselective hydrogenation of a-dehydroamino acids and itaconic acid derivatives [25],... 

Feringa and co-workers developed an efficient methodology for conjugate addition of dialkylzinc reagents to enones catalyzed by copper(II) and the remarkably versatile chiral monophosphoramidite ligand 27 (Scheme 12.6) [18]. 

Chiral monophosphoramidites were the first type of highly efficient monodentate... 

Monophosphoramidites can be prepared in different ways. The most common route... 

Scheme 8.5 Asymmetric hydrogenation of cyclic enamides with monophosphoramidite ligands.

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