Recent developments in the synthesis of chiral phosphorus ligands are summarized. Main emphasis is given to the multitude of protocols for their synthesis starting from compounds of the chiral pool or by using other easily available chiral starting materials. Besides mono-and bidentate P-ligands hybrid ligands bearing N, O, or olefinic groups as second ligating units are addressed. The syntheses of new P-chirogenic ligands, as well as ligands with supramolecular structures are likewise reviewed. In appropriate cases structures of related privileged ligands are given for comparison. When available, the efficiency of the new ligands for metal catalyzed reactions are briefly assessed.[a] Dr.
The rhodium-catalyzed hydroformylation of methyl oleate (MO) with new monodentate phosphoramidite ligands 1a−d is investigated here. The ligands are characterized by lactam rings of different size (four-to seven-membered rings). In mild conditions (synthesis gas pressure: 30 bar, 80 °C), the rhodium catalysts based on the P-azetidinone phosphoramidite 1a gave within 6 h complete conversion and produced mainly methyl 9-and 10-formylstearate (MFS) with 99% chemoselectivity. In the hydrolysis test, phosphoramidite 1a was also the most stable. This was additionally confirmed by density functional theory calculations.
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