DuPhos monoxide

Both Me-DuPHOS (483) and Me-DuPHOS monoxide (484) have been successfully used as chiral ligands in the copper catalysed highly enantio-selective addition of dialkylzinc to N-phosphinoyl imines (485). A simple deprotection of N-protecting group from (486) provided a-chiral amines (Figure 91). ... 

A solution to the nonreactive nature of phenylsulfones has been found the hemilabile bidentate ligand methyl DuPHOS monoxide [Me-DuPHOS(O)], together... 

Asymmetric [4+1] cycloaddition of vinylallenes and carbon monoxide is promoted by a cationic Rh complex formed in situ from [Rh(cod)2]PF6 and chiral diphosphine ligand, (R.R)-Me-DuPHOS to afford 2-alkylidene-3-cyclopentenones with high asymmetric induction [72] (Eq. 8A.48). 

The catalyst [Pd(Me-DUPHOS)(MeCN)2](BF4)2 was also effective in the alternating asymmetric copolymerization of aliphatic a-olefins with carbon monoxide [27,28]. The polymer synthesized in a CH3N02-CH30H mixture has both 1,4-ketone and spiroketal (10) units in the main chain. The propylene-CO copolymer consisting only of a 1,4-ketone structure shows [ ]D +22° (in (CF3)2CHOH), and the optical purity of the main chain chiral centers is over 90% as estimated by NMR analysis using a chiral Eu shift reagent. 

In addition to hydrogenation reactions, modular phospholane ligands are being applied in a growing rank of other useful asymmetric catalytic transformations. For instance, Jiang and Sen reported the discovery of a dicationic Me-DuPhos-Pd catalyst for the alternating copolymerization of aliphatic a-olefins and carbon monoxide (Scheme 13.21).67... 

Murakami and Ito have highlighted the utility of cationic Me-DuPhos-Rh catalysts for novel asymmetric (4 + 1) cycloaddition reactions between vinylallenes and carbon monoxide.68 Complex cyclopentenone derivatives such as 64 have been constructed in a single step and with enantiose-lectivities up to 95% in this process (Scheme 13.22). 

Figure 10 Functionalized olefins copolymerized with carbon monoxide by Pd complex bearing Me-DUPHOS or BINAPHOS.

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