AMPP ligands

Scheme 33.5 One-pot, two-step procedure for the synthesis of mixed AMPP ligands.

Scheme 33.6 AMPP ligands synthesized from amino alcohols.

In recent years, much effort has been devoted to the enantioselective hydrogenation of yS-ketoesters, essentially using ruthenium-based catalysts. The aim of these reactions is to produce selectively enantiopure syn diols which are the key building blocks for the synthesis of inhibitors of HMG-coenzyme A reductase. Due to the availability of the AMPP ligands, and the reactivity of the rhodium catalysts based on them (notably the alkyl-substituted ones) towards ketonic sub-... 

The (2S,4S)-MCCPM-Rh(I) complex was found previously by Achiwa and colleagues to be an efficient catalyst for the enantioselective hydrogenation of /9-amino ketone derivatives, leading to a practical enantioselective synthesis of (F)-fluoxetine [N-methyl-3-(4-trifluoromethylphenoxy)-3-phenylpropylamine] hydrochloride [22 b]. Moreover, the use of AMPP ligands again proved to be efficient for these substrates, as exemplified in Table 33.6 [15 i],... 

In further investigations, AMPP ligands derived from linear amino acids and several 3,l,2-oxazaphosphabicyclo[3.3.0]octanes (derived from proline) were used for the same cy-clodimerization reaction catalyzed by bis(l,5-cyclooctadiene)nickel(0). Optical yields were as high as 26% if (2R,3/ )-Threophos, an aminophosphane-diphosphinite ligand derived from threonine, was used58 63. 

Aminophosphine phosphinite (AMPP) ligands constitute an important class of non-C2 diphosphorus ligands. Some of them are prepared from ephedrine and therefore the Juge-Stephan method constitutes an ideal procedure for the synthesis of P-stereogenic AMPP ligands (Scheme 4.30). ... 

In the consecutive hydrogenation of />,<5-diketo esters (Table 21.16), selection of the chiral ligand can determine the sense of diastereoselection, and the 3,5-syn dihydroxy product was formed predominantly upon use of a Ru-(S)-amino-phosphinephosphinite-((S)-AMPP) catalyst, although the enantioselectivity of the syn-product is poor (Table 21.16, entry 7) [103a]. Syn 3,5-diol formation... 

Amino acid derived chiral aminophosphane phosphinites (AMPP) such as Ephos, Proliphos, Glyphos and others1 " 128,195 constitute another new type of chiral phosphane ligand used in asymmetric hydroformylation with rhodium complexes 127,128 and platinum salts113. 

Chiral ligands can be varied with rhodium catalysts modifications with Diop, Diop-DBP and other variants of Diop, Chiraphos, BPPM, BnCH3PhP, CH3PrPhP, NMDPP, and AMPP type ligands are reported (for abbreviations and literature see Section 1.5.8.2.2.2.). Polymer-supported catalysts are mainly used as non-cross-linked polystyrene with attached phosphane ligands, among others Diop and BPPM9 62,153-155. Aspects of these variations are discussed below under platinum catalysts). 

Precursors of the type [RhCl(alkene)2]2 are also used, e.g., [RhCl(C,H4),]2 with Diop151, AMPP-type ligands such as Ephos, Proliphos and others128, [Rh(I,5-hexadiene)Cl]2 with BnCH3PhP118, [Rh(nbd)CI], with Chiraphos44, and [Rh(nbd)]BF4 with a.a -TREDIP and /i,/ -TREDIP25. 

Chiral aminophosphane-phosphinites (AMPP), prepared by the reaction of chloro(diphenyl)-phosphane with optically active amino alcohols, such as ephedrines, prolinol and A -methyl-phenylglycinol, are used as ligands in transition metal catalyzed cyclodimerization of butadiene to 4-vinylcyclohexene62,10 . With a nickel(0)LJ catalyst (L = Proliphos), (—)-4-vinylcyclo-hexene with 15% ee was obtained in 50% yield6. ... 

Chiral ligands containing tervalent phosphorus acid derivatives as coordination sites continue to be explored for asymmetric metal catalysed reactions. New examples this year include the phosphite (119) and stereoisomers, the phosphites (120), 2 the diphosphinite TADDOP (121), the diphosphites (122) containing crown ethers, the aminophosphine-phosphinites AMPP s (123) and... 

Also, aminophosphine-phosphinites 1 (AMPPs), originally developed as ligands for asymmetric hydrogenation by the Lyon group of Agbossou-Niedercorn and Mortreux [47, 48], have been tested in asymmetric hydroformylation with a tin-free Pt catalyst (Pigure 1.13). 

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