Rhodium-Catalyzed Nonisomerizing Hydroformylation of Methyl Oleate Applying Lactame-Based Phosphoramidite Ligands

Abstract

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.