The asymmetric hydroformylation reaction represents a potential powerful synthetic tool for the preparation of large number of different chiral products to be used as precursors of several organic compounds endowed with therapeutic activity. Essential and nonessential amino acids, 2-arylpropanoic acids, aryloxypropyl- and beta-phenylpropylamines, modified beta-phenylethylamines, pheniramines, and other classes of pharmaceuticals are available through enantioselective oxo-reaction of appropriate functionalized olefins; this process is catalyzed by rhodium or platinum complexes with chiral ligands, mainly chelating phosphines, and sometimes affords very high enantiomeric excesses. Furthermore, the application of many simple optically active aldehydes arising from asymmetric hydroformylation as chiral building blocks for the synthesis of complex pharmacologically active molecules such as antibiotics, peptides, antitumor macrocycle compounds, and prostaglandins is conveniently emphasized. The possibility of a future application of this asymmetric process for the production of many synthons to obtain other valuable pharmaceuticals is widely discussed too.

The water‐soluble complex derived from Rh(CO)2(acac) and human serum albumin (HSA) proved to be efficient in the hydroformylation of several olefin substrates. The chemoselectivity and regioselectivity were generally higher than those obtained by using the classic catalytic systems like TPPTS‐Rh(I) (TPPTS=triphenylphosphine‐3,3′,3″‐trisulfonic acid trisodium salt). Styrene and 1‐octene, for instance, were converted in almost quantitative yields into the corresponding oxo‐aldehydes at 60 °C and 70 atm (CO/H2=1) even at very low Rh(CO)2(acac)/HSA catalyst concentrations. The possibility of easily recovering the Rh(I) compound makes the system environmentally friendly. The circular dichroism technique was useful for demonstrating the Rh(I) binding to the protein and to give information on the stability in solution of the catalytic system. Some other proteins have been used to replace HSA as complexing agent for Rh(I). The results were less impressive than those obtained using HSA and their complexes with Rh(I) were much less stable.

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