Synthesis of meta-substituted monodentate phosphinite ligands and implication in hydroformylation $$^\dagger $$ †

Abstract

Synthesis of meta-substituted phosphinite ligands 3,3-(methoxyphosphanediyl)bis(N ,Ndiethylaniline) (4a) and methoxybis(3-methoxyphenyl)phosphane (4b), in high yields, has been demonstrated. Typical phosphorus chemical shift between 110-120 ppm, appearance of methoxy protons and corresponding carbon, as well as ESI-MS spectra unambiguously confirmed the existence of phosphinite ligands 4a and 4b. To demonstrate the synthetic usefulness of 4a and 4b, these ligands were tested in the rhodium catalyzed hydroformylation of 1-octene. The diethylamine substituted ligand 4a was found to be highly active, whereas 4b was less reactive but revealed slightly better regioselectivity of 62% under optimized conditions. Additionally, 4a and 4b were found to catalyze the hydroformylation of styrene, 1-undecenol and 1,1-disubstituted functional olefin, methyl methacrylate. Both the ligands displayed excellent conversion of styrene, and 4b revealed an excellent branch selectivity of 75%. Although 1-undecenol proved to be amenable to hydroformylation (85-90% conversion to aldehyde), both the ligands failed to discriminate between the linear and branched products. Substrate methyl methacrylate proved to be highly challenging and reduced conversion (between 33-42%) was observed under optimized conditions. Ligand 4a was found to be highly selective towards linear aldehyde (81% linear selectivity).

Iron Catalyzed Hydroformylation of Alkenes under Mild Conditions: Evidence of an Fe(II) Catalyzed Process

“…Guided by these reports, we anticipated that the best way to manipulate the reactivity of 1 would be to offer a competitive ligand to replace carbonyls and activate 1 in situ . Phosphorus ligands such as phosphines, phosphites, phosphinites, diphosphines, diphosphites, phosphine-phosphonite, phosphine-phosphoramidite and phosphine-phosphite have been extensively utilized in rhodium catalyzed hydroformylation. Thus, given the success of the phosphorus ligand in hydroformylation, we zeroed in on readily accessible σ-donor ligands such as phosphines and σ-donor π-acceptor ligands such as phosphites .…”

Phosphorus Ligands in Hydroformylation and Hydrogenation: A Personal Account

“…The optimized reaction conditions were found to be, a ligand to metal ratio of ‘4’; syngas pressure of ”10 bar“, and temperature of “100 °C“. The scope of the hydroformylation was broadened and various substrates as listed in Table 1 were subjected to hydroformylation [52] …”

Rhodium/Phosphine catalysed selective hydroformylation of biorenewable olefins

“…Hydroformylation of olefins represents one of the most significant and largest homogeneous catalytic industrial process for the production of oxochemicals produced 10–12 million tonnes every year . Since it was invented by Otto Roelen in 1938, this transformation has been widely explored and has made great progress in recent decades . It is also called as oxo process for the conversion of olefins into aldehydes, alcohols, carboxylic acid and derivatives in presence of transition metal catalyst under syngas (CO/H 2 ) pressure .…”