4254-15-3Relevant articles and documents
Stereochemistry of Nucleophilic Displacement on Two Phosphoric Monoesters and a Phosphoguanidine: The Role of Metaphosphate
Buchwald Stephen L.,Friedman, Jonathan M.,Knowles, Jeremy R.
, p. 4911 - 4916 (1984)
For the role of monomeric metaphosphate and the nature of the transition states in the alcoholysis of phosphoric monoesters to be examined, phenyl phosphate and 2,4-dinitrophenyl phosphate have been synthesized and the stereochemical course of the methanolysis of phenyl phosphate monoanion and of dinitrophenyl phosphate dianion has been evaluated. Phosphocreatine has also been synthesized and the stereochemical course of the methanolysis of this molecule determined.In each case, complete inversion of configuration at phosphorus is observed.It is clear that metaphosphate, if it exists as a true intermediate in these reactions in protic solvent, does not leave the solvent cage in which it is generated.Indeed, product formation occurs more rapidly than rotation of the putative metaphosphate intermediate.These displacements must therefore occur by preassociative mechanisms in which there may be some assistance from the incoming nucleophile.The present results do not allow a distinction to be made between a "preassociative concerted" path (that is, an SN2-like displacement via a very loose transition state) and a "preassociative stepwise" path via a metaphosphate intermediate of very short lifetime.
THE CONFIGURATIONS OF (-)-2,3,3-TRIMETHYL-2-HYDROXYBUTANOIC ACID, Me3CC(Me)(OH)CO2H, (-)-3,3,4-TRIMETHYL-3-HYDROXY-1-PENTYNE AND (-)-3-t-BUTYL-3-METHYL-1-CHLOROALLENE
Eliel, Ernest L.,Lynch, Joseph E.,Kenan, William R.
, p. 4813 - 4816 (1987)
The configurations of the title compounds are reassigned, based on stereoselective syntheses of the hydroxyacid and corresponding glycol and application of Cram's, Prelog's and Sharpless' rules.
Mild electrocatalytic hydrogenation of lactic acid to lactaldehyde and propylene glycol
Dalavoy, Tulika S.,Jackson, James E.,Swain, Greg M.,Miller, Dennis J.,Li, Jie,Lipkowski, Jacek
, p. 15 - 28 (2007)
Reduction of fermentation-derived lactic acid (LA) offers a renewables-based pathway to propylene glycol (PG), a large-scale commodity chemical, currently manufactured by the oxidation of petroleum-derived propene. Complementing our previously described catalytic hydrogenation of LA to PG, we now report electrocatalytic hydrogenation (ECH) of LA in an aqueous electrolyte using constant current electrolysis. A reticulated vitreous carbon (RVC) electrode serves to agglomerate, support, and supply current to a 5% Ru/C powder catalyst, the same catalyst used in the classical hydrogenations. The ECH conditions are mild (ambient pressure, 70 °C vs 1500 psi H2, 150 °C) relative to the chemical hydrogenation. More surprisingly, the major electrohydrogenation product is lactaldehyde (LAL), with small quantities of PG also formed. Variable current studies in the range of 10-100 mA show an increase in product yields and a shift in selectivity toward PG with increasing current. Experiments carried out with different acids as electrolytes reveal a distinct effect of the anion on the yields of the two products. In situ ATR-FTIR studies of the ECH of LA point to a chelating bidentate carboxylate adsorption mode for lactate on the Ru surface and offer insight into the effects of electrolyte anions on surface adsorption and reactivity.
Enantiodivergent syntheses of (+)- and (?)-1-(2,6-dimethylphenoxy)propan-2-ol: A way to access (+)- and (?)-mexiletine from D-(+)-mannitol
Manna, Avrajit,Chatterjee, Sandip,Chakraborty, Ipsita,Bhaumik, Tanurima
, (2020/01/08)
Chiron approach was used to acquire optically pure (R)- and (S)-1-(2,6-dimethylphenoxy)propan-2-ol, immediate precursors of (S)- and (R)-mexiletines, respectively. Two different routes were followed from a D-mannitol-derived optically pure common precursor to get the enantiomeric alcohols separately. Comparison of their specific rotation values with the corresponding literature values as well as exact mirror-image relationship between their CD curves proved their high enantiopurity. These alcohols were then transformed to the corresponding amine-drugs in an efficient one-step process instead of two steps described in the literature.
Encapsulation of Homogeneous Catalysts in Mesoporous Materials Using Diffusion-Limited Atomic Layer Deposition
Zhang, Shufang,Zhang, Bin,Liang, Haojie,Liu, Yequn,Qiao, Yan,Qin, Yong
supporting information, p. 1091 - 1095 (2018/01/01)
The heterogenization of homogeneous metal complex catalysts has attracted great attention. The encapsulation of metal complexes into nanochannels of mesoporous materials is achieved by coating metal oxides at/near the pore entrance by diffusion-limited atomic layer deposition (ALD) to produce a hollow plug. The pore size of the hollow plug is precisely controlled on the sub-nanometer scale by the number of ALD cycles to fit various metal complexes with different molecular sizes. Typically, Co or Ti complexes are successfully encapsulated into the nanochannels of SBA-15, SBA-16, and MCM-41. The encapsulated Co and Ti catalysts show excellent catalytic activity and reusability in the hydrolytic kinetic resolution of epoxides and asymmetric cyanosilylation of carbonyl compounds, respectively. This ALD-assisted encapsulation method can be extended to the encapsulation of other homogeneous catalysts into different mesoporous materials for various heterogeneous reactions.