22160-39-0Relevant articles and documents
Functionalization of α-C(sp3)?H Bonds in Amides Using Radical Translocating Arylating Groups
Radhoff, Niklas,Studer, Armido
supporting information, p. 3561 - 3565 (2021/01/04)
α-C?H arylation of N-alkylamides using 2-iodoarylsulfonyl radical translocating arylating (RTA) groups is reported. The method allows the construction of α-quaternary carbon centers in amides. Various mono- and disubstituted RTA-groups are applied to the arylation of primary, secondary, and tertiary α-C(sp3)?H-bonds. These radical transformations proceed in good to excellent yields and the cascades comprise a 1,6-hydrogen atom transfer, followed by a 1,4-aryl migration with subsequent SO2 extrusion.
Preparation method of 2-R1 valeric acid
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, (2021/07/24)
The invention discloses a preparation method for 2-R1 valeric acid. The preparation method comprises the following steps: step 1, with methyl cyanoacetate as a starting material, adding bromopropane and sodium methoxide, carrying out a catalytic reaction, and conducting purifying to obtain 2-cyanomethyl valerate; step 2, subjecting 2-cyanomethyl valerate to a reaction under the catalysis of iodoalkane and sodium methoxide, and conducting aftertreatment to obtain 2-cyano-2-R1 methyl valerate; step 3, enabling the 2-cyano-2-R1 methyl valerate to undergo a reaction in an aqueous solution of sulfuric acid at 120-160 DEG C for 15-40 hours so as to obtain a mixture of 2-R1 valeric acid and 2-R1 methyl valerate; and step 4, hydrolyzing the mixture by using an aqueous sodium hydroxide solution to obtain 2-R1 sodium valerate and methanol, and conducting acidifying by using inorganic acid to obtain 2-R1 valeric acid. Reagents adopted in the preparation method are relatively common, and the risk of the reagents is relatively low; and reaction conditions are mild, and the temperature is easier to control relatively. The invention develops a purification process of the key intermediate 2-cyanomethyl valerate, and the process flow is simple.
Cobalt-Catalyzed Asymmetric Hydrogenation of α,β-Unsaturated Carboxylic Acids by Homolytic H2 Cleavage
Chirik, Paul J.,Shevlin, Michael,Zhong, Hongyu
supporting information, (2020/03/13)
The asymmetric hydrogenation of α,β-unsaturated carboxylic acids using readily prepared bis(phosphine) cobalt(0) 1,5-cyclooctadiene precatalysts is described. Di-, tri-, and tetra-substituted acrylic acid derivatives with various substitution patterns as well as dehydro-α-amino acid derivatives were hydrogenated with high yields and enantioselectivities, affording chiral carboxylic acids including Naproxen, (S)-Flurbiprofen, and a d-DOPA precursor. Turnover numbers of up to 200 were routinely obtained. Compatibility with common organic functional groups was observed with the reduced cobalt(0) precatalysts, and protic solvents such as methanol and isopropanol were identified as optimal. A series of bis(phosphine) cobalt(II) bis(pivalate) complexes, which bear structural similarity to state-of-the-art ruthenium(II) catalysts, were synthesized, characterized, and proved catalytically competent. X-band EPR experiments revealed bis(phosphine)cobalt(II) bis(carboxylate)s were generated in catalytic reactions and were identified as catalyst resting states. Isolation and characterization of a cobalt(II)-substrate complex from a stoichiometric reaction suggests that alkene insertion into the cobalt hydride occurred in the presence of free carboxylic acid, producing the same alkane enantiomer as that from the catalytic reaction. Deuterium labeling studies established homolytic H2 (or D2) activation by Co(0) and cis addition of H2 (or D2) across alkene double bonds, reminiscent of rhodium(I) catalysts but distinct from ruthenium(II) and nickel(II) carboxylates that operate by heterolytic H2 cleavage pathways.
