93-60-7Relevant articles and documents
GC-FID-based quantification of the sum of the three forms of vitamin B3 from animal liver
H?mmerle, Michael,Hekmat, Omid,Le, Minh Hien
, (2020)
Vitamin B3 (nicotinic acid, nicotinamide) is an essential water-soluble vitamin and cellular energy metabolism depends on the vitamin B3-derived cofactors. Inaccessible covalently-linked nicotinic acid in food such as maize can cause vitamin B3 deficiency in animals since maize is also deficient in tryptophan, the precursor of nicotinic acid. A sensitive and reproducible GC-FID-based method for the quantification of the sum of the three forms of vitamin B3 from animal liver was developed. Free nicotinic acid, free nicotinamide and nicotinamide moiety of NAD+/NADP+ (and their riboside precursors) were simultaneously derivatized as methyl nicotinate. Reaction time and temperature and the extraction procedure for methyl nicotinate were optimized. Starting from wild boar liver, removal of proteins, solvent exchange, derivatization, and chloroform extraction resulted in sufficient enrichment and baseline separation of methyl nicotinate. The within-laboratory reproducibility of the full procedure was determined with RSD 3 standards. The overall recovery for the full procedure was 16% but very consistent (RSD = 7%), enabling determination of apparent vitamin B3 concentrations for relative quantitative comparison.
Metal analyses in environmental and pharmaceutical samples by capillary electrophoresis with methyl 3-amino-3-(pyridin-3-yl)propanoate dihydrochloride as a new ion-pairing reagent
Belin, Gamze Kavran,Guelacar, Fazil Osman
, p. 2322 - 2332 (2005)
Separation and determination of some common metal ions was achieved with methyl 3-amino-3-( pyridin-3-yl)propanoate dihydrochloride (MAPP) as an ion-pairing reagent and pyridine as a detectable counter-ion for indirect UV detection at 254 nm. The effects of the complexing reagent and chromophore concentrations, applied voltage, and organic solvent content on the separation were investigated. The optimized separation was carried out in a running electrolyte containing 16 mM MAPP and 20 mM pyridine at pH 4.0 and was successfully applied to the qualitative and quantitative analysis of Li +, Na+, Mg2+, Ca2+, Ba2+, Ni2+, and Zn2+ in pharmaceutical vitamin preparations and various water samples.
Minisci-Type Alkylation of N-Heteroarenes by N-(Acyloxy)phthalimide Esters Mediated by a Hantzsch Ester and Blue LED Light
Kyne, Sara Helen,Li, Jiacheng,Siang Tan, Suan,Wai Hong Chan, Philip
supporting information, (2022/01/11)
A synthetic method that enables the Hantzsch ester-mediated Minisci-type C2-alkylation of quinolines, isoquinolines and pyridines by N-(acyloxy)phthalimide esters (NHPI) under blue LED (light emitting diode) light (456 nm) is described. Achieved under mild reaction conditions at room temperature, the metal-free synthetic protocol was shown to be applicable to primary, secondary and tertiary NHPIs to give the alkylated N-heterocyclic products in yields of 21–99%. On introducing a chiral phosphoric acid, an asymmetric version of the reaction was also realised and provided product enantiomeric excess (ee) values of 53–99%. The reaction mechanism was delineated to involve excitation of an electron-donor acceptor (EDA) complex, formed from weak electrostatic interactions between the Hantzsch ester and NHPI, which generates the posited radical species of the redox active ester that undergoes addition to the N-heterocycle.
Highly chemoselective deoxygenation of N-heterocyclic: N -oxides under transition metal-free conditions
Kim, Se Hyun,An, Ju Hyeon,Lee, Jun Hee
supporting information, p. 3735 - 3742 (2021/05/04)
Because their site-selective C-H functionalizations are now considered one of the most useful tools for synthesizing various N-heterocyclic compounds, the highly chemoselective deoxygenation of densely functionalized N-heterocyclic N-oxides has received much attention from the synthetic chemistry community. Here, we provide a protocol for the highly chemoselective deoxygenation of various functionalized N-oxides under visible light-mediated photoredox conditions with Na2-eosin Y as an organophotocatalyst. Mechanistic studies imply that the excited state of the organophotocatalyst is reductively quenched by Hantzsch esters. This operationally simple technique tolerates a wide range of functional groups and allows high-yield, multigram-scale deoxygenation. This journal is
Metal-Free Heterogeneous Semiconductor for Visible-Light Photocatalytic Decarboxylation of Carboxylic Acids
Shi, Jiale,Yuan, Tao,Zheng, Meifang,Wang, Xinchen
, p. 3040 - 3047 (2021/03/09)
A suitable protocol for the photocatalytic decarboxylation of carboxylic acids was developed with metal-free ceramic boron carbon nitrides (BCN). With visible light irradiation, BCN oxidize carboxylic acids to give carbon-centered radicals, which were trapped by hydrogen atom donors or employed in the construction of the carbon-carbon bond. In this system, both (hetero)aromatic and aliphatic acids proceed the decarboxylation smoothly, and C-H, C-D, and C-C bonds are formed in moderate to high yields (35 examples, yield up to 93%). Control experiments support a radical process, and isotopic experiments show that methanol is employed as the hydrogen atom donor. Recycle tests and gram-scale reaction elucidate the practicability of the heterogeneous ceramic BCN photoredox system. It provides an alternative to homogeneous catalysts in the valuable carbon radical intermediates formation. Moreover, the metal-free system is also applicable to late-stage functionalization of anti-inflammatory drugs, such as naproxen and ibuprofen, which enrich the chemical toolbox.
