40630-07-7Relevant academic research and scientific papers
Highly regioselective rhodium-catalysed hydroformylation of unsaturated Esters: The first practical method for quaternary selective carbonylation
Clarke, Matthew L.,Roff, Geoffrey J.
, p. 7978 - 7986 (2007/10/03)
Highly regioselective hydroformylation of unsaturated esters can be achieved when a highly reactive, ligand-modified, rhodium catalyst is employed near ambient temperatures (15-50°C) and pressures over 30 bar. The use of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane shows distinct advantages over other commonly applied phosphanes in terms of reaction rate, and regio- and chemoselectivity. Hydroformylation of a range 1,1-di- and 1,1,2-trisubstituted unsaturated esters yields quaternary aldehydes that are forbidden products according to Keulemans Rule. The aldehydes can be reductively aminated with molecular hydrogen to give β-amino acid esters in high yield. The overall green chemical process involves converting terminal alkynes into unusual β-amino acid esters with only water generated as an essential byproduct. This catalytic system has also been applied to the hydroformylation of simple 1,2-disubstitued unsaturated esters, which have been hydroformylated with excellent α-selectivity and good chemo-selectivity for the first time.
Highly regioselective hydroformylation of internal, functionalized olefins applying Pt/Sn complexes with large bite angle diphosphines
Meessen, Patric,Vogt, Dieter,Keim, Wilhelm
, p. 165 - 170 (2007/10/03)
The regioselective hydroformylation of methyl 3-pentenoate (M3P) leading to linear 5-formyl methyl pentanoate (3-FMP) was studied. For this purpose Pt/Sn catalyst systems were modified by diphosphine ligands derived from heteroaromatic xanthene-type hydrocarbons. These xantphos ligands possess a large bite angle combined with a rigid backbone. The (P∩P)PtCl2 catalyst precursor complexes were prepared and characterized by 1H- and 31P NMR-spectroscopy. The catalysts show unprecedented high regioselectivity to the terminal aldehyde. In addition, the undesired hydrogenation of the substrate and the products is largely suppressed. It was shown that activity as well as selectivity are controlled both by the bite angle and the rigidity of the backbone of the ligands.
