431-46-9Relevant articles and documents
SYNTHESIS OF FLUORO HEMIACETALS VIA TRANSITION METAL-CATALYZED FLUORO ESTER AND CARBOXAMIDE HYDROGENATION
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Paragraph 0245-0250; 0261, (2020/11/24)
This application is directed to use of transition metal-ligand complexes to hydrogenate fluorinated esters and carboxamides into fluorinated hemiacetals. Methods for synthesis of certain ligands are also provided.
Optimization and sustainability assessment of a continuous flow Ru-catalyzed ester hydrogenation for an important precursor of a β2-adrenergic receptor agonist
García-Lacuna, Jorge,Hone, Christopher A.,Kappe, C. Oliver,Leslie, Kevin,Munday, Rachel,O'Kearney-McMullan, Anne,Prieschl, Michael
supporting information, p. 5762 - 5770 (2020/09/21)
The development of a ruthenium-catalyzed continuous flow ester hydrogenation using hydrogen (H2) gas is reported. The reaction was utilized for the reduction of an important precursor in the synthesis of abediterol, a β2-adrenoceptor agonist that has undergone phase IIa clinical trials for the treatment of asthma and chronic obstructive pulmonary disorder. The reaction was investigated within a batch autoclave by using a design of experiments (DoE) approach to identify important parameter effects. The optimized flow process was successfully operated over 6 h with inline benchtop19F NMR spectroscopy for reaction monitoring. The protocol is shown to be high yielding (98% yield, 3.7 g h?1) with very low catalyst loading (0.065 mol%). The environmental impact of the Ru-catalyzed hydrogenation was assessed and compared to an existing stoichiometric lithium aluminum hydride (LAH) reduction and sodium borohydride (NaBH4) reduction. The process mass intensity (PMI) for the Ru-catalyzed hydrogenation (14) compared favorably to a LAH reduction (52) and NaBH4reduction (133).
Why does alkylation of the N-H functionality within M/NH bifunctional Noyori-type catalysts lead to turnover?
Dub, Pavel A.,Scott, Brian L.,Gordon, John C.
supporting information, p. 1245 - 1260 (2017/05/16)
Molecular metal/NH bifunctional Noyori-type catalysts are remarkable in that they are among the most efficient artificial catalysts developed to date for the hydrogenation of carbonyl functionalities (loadings up to ～10-5 mol %). In addition, these catalysts typically exhibit high C=0/C=C chemo- and enantioselectivities. This unique set of properties is traditionally associated with the operation of an unconventional mechanism for homogeneous catalysts in which the chelating ligand plays a key role in facilitating the catalytic reaction and enabling the aforementioned selectivities by delivering/accepting a proton (H+) via its N-H bond cleavage/formation. A recently revised mechanism of the Noyori hydrogenation reaction (Dub, P. A et al. J. Am. Chem. Soc. 2014,136,3505) suggests that the N-H bond is not cleaved but serves to stabilize the turnover-determining transition states (TDTSs) via strong N-H···O hydrogen-bonding interactions (HBIs). The present paper shows that this is consistent with the largely ignored experimental fact that alkylation of the N-H functionality within M/NH bifunctional Noyori-type catalysts leads to detrimental catalytic activity. The purpose of this work is to demonstrate that decreasing the strength of this HBI, ultimately to the limit of its complete absence, are conditions under which the same alkylation may lead to beneficial catalytic activity.
