Vinyl rhodium-catalyzed asymmetric

Rhodium-Catalyzed Asymmetric Hydroformylation of Vinyl Arenes. .. 41... 

Scheme 3 Model rhodium-catalyzed asymmetric hydroformylation asymmetric of vinyl...

The bisferrocenylbisphosphine 15 has been reported to be an enantioselective chiral ligand for the rhodium-catalyzed asymmetric Michael addition of a-cyano carboxy-lates [85] to vinyl ketones (Scheme 2-60). The tranj-chelation of 15 generates efficient chiral surroundings around the rhodium atom to produce a quaternary chiral carbon center with up to 89% ee. 

Most of the reports on Rh-catalyzed asymmetric hydroformylation are concerned with asymmetric hydroformylation of vinyl aromatics, which are model substrates of interest to the pharmaceutical industry. In 1993 and 1995, reports were published describing the state of the art in hydroformylation with both rhodium and platinum systems.80,81 310 Two reports appeared in 1999 and 2000 on carbonylation and rhodium asymmetric hydroformylation respectively.311,345... 

The asymmetric hydroformylation of functionalized aliphatic alkenes is generally more difficult than the hydroformylation of vinyl arenes. The rhodium-catalyzed hydroformylation of vinyl acetate (36) yields 2- and 3-acetoxypropanals, 37 and 38, with high chemoselectivity. Ethyl acetate and acetic acid can also be found as by-products. One of the potential applications of vinyl acetate hydroformylation is the production of enantiopure propane 1,2-diol (Scheme 6). 

Boronic esters have been used in a wide range of transformations. These useful reagents have been transformed into numerous functional groups and are essential reagents for several C-C bond-forming reactions. Transition metal-catalyzed hydroboration of olefins often leads to mixtures of branched and linear products. Several groups have reported asymmetric reductions of vinyl boronic esters [50-52] with chiral rhodium P,P complexes however, the first iridium-catalyzed reduction was reported by Paptchikhine et al (Scheme 10) [53]. 

The asymmetric hydroformylation of //-substituted 4-vinyl (3-lactams, catalyzed by rhodium(I) complexes, leading to l-(3-methylcarbapenem precursors (VI, Fig. 16) has been reported [285]. 

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