539-32-2Relevant articles and documents
Interconversion of nicotine enantiomers during heating and implications for smoke from combustible cigarettes, heated tobacco products, and electronic cigarettes
Moldoveanu, Serban C.
, p. 667 - 677 (2022/02/02)
Physiological properties of (R)-nicotine have differences compared with (S)-nicotine, and the subject of (S)- and (R)-nicotine ratio in smoking or vaping related items is of considerable interest. A Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) method for the analysis of (S)- and (R)-nicotine has been developed and applied to samples of nicotine from different sources, nicotine pyrolyzates, several types of tobacco, smoke from combustible cigarettes, smoke from heated tobacco products, e-liquids, and particulate matter obtained from e-cigarettes aerosol. The separation was achieved on a Chiracel OJ-3 column, 250 × 4.6 mm with 3-μm particles using a nonaqueous mobile phase. The detection was performed using atmospheric pressure chemical ionization (APCI) in positive mode. The only transition measured for the analysis of nicotine was 163.1 → 84.0. The method has been summarily validated. For the analysis, the samples of tobacco and smoke from combustible cigarettes were subject to a cleanup procedure using solid phase extraction (SPE). It was demonstrated that nicotine upon heating above 450°C for several minutes starts decomposing, and some formation of (R)-enantiomer from a sample of 99% (S)-nicotine is observed. An analogous process takes place when a 99% (R)-nicotine is heated and forms low levels of (S)-nicotine. This interconversion has the effect of slightly increasing the content of (R)-nicotine in smoke compared with the level in tobacco for combustible cigarettes and for heated tobacco products. The (S)/(R) ratio of nicotine enantiomers in e-liquids was identical with the ratio for the particulate phase of aerosols generated by e-cigarette vaping.
Ligand assessment for the suzuki-miyaura cross coupling reaction of aryl and heteroaryl bromides with n-butylboronic acid. The advantages of buchwald's s-phos
Jagusch, Thomas,Lehnemann, Bernd,Meudt, Andreas,Nerdinger, Sven,Neuner, Sandro,Scherer, Stefan,Schottenberger, Herwig,Snieckus, Victor
, p. 631 - 644 (2020/01/31)
An investigation of biarylphosphine ligands for the Suzuki-Miyaura cross coupling reaction of aryl and heteroaryl bromides with n-butylboronic acid is presented. The results obtained on ligand modification and aryl as well as heteroaryl bromides variation represent a significant improvement in the state of the art of alkylboronic acid cross coupling methodology.
Manganese-Catalyzed Kumada Cross-Coupling Reactions of Aliphatic Grignard Reagents with N-Heterocyclic Chlorides
Petel, Brittney E.,Purak, Merjema,Matson, Ellen M.
supporting information, p. 1700 - 1706 (2018/07/13)
Herein we report the use of manganese(II) chloride for the catalytic generation of C(sp 2)-C(sp 3) bonds via Kumada cross-coupling. Rapid and selective formation of 2-alkylated N-heterocyclic complexes were observed in high yields with use of 3 mol% MnCl 2 THF 1.6 and under ambient reaction conditions (21 °C, 15 min to 20 h). Manganese-catalyzed cross-coupling is tolerant toward both electron-donating and electron-withdrawing functional groups in the 5-position of the pyridine ring, with the latter resulting in an increased reaction rate and a decrease in the amount of nucleophile required. The use of this biologically and environmentally benign metal salt as a catalyst for C-C bond formation highlights its potential as a catalyst for the late-stage functionalization of pharmaceutically active N-heterocyclic molecules (e.g., pyridine, pyrazine).
Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
, p. 1996 - 2003 (2017/02/26)
Here, we describe a photoredox-assisted catalytic system for the direct reductive coupling of two carbon electrophiles. Recent advances have shown that nickel catalysts are active toward the coupling of sp3-carbon electrophiles and that well-controlled, light-driven coupling systems are possible. Our system, composed of a nickel catalyst, an iridium photosensitizer, and an amine electron donor, is capable of coupling halocarbons with high yields. Spectroscopic studies support a mechanism where under visible light irradiation the Ir photosensitizer in conjunction with triethanolamine are capable of reducing a nickel catalyst and activating the catalyst toward cross-coupling of carbon electrophiles. The synthetic methodology developed here operates at low 1 mol % catalyst and photosensitizer loadings. The catalytic system also operates without reaction additives such as inorganic salts or bases. A general and effective sp2-sp3 cross-coupling scheme has been achieved that exhibits tolerance to a wide array of functional groups.
Iron-catalyzed cross-coupling reactions of alkyl grignards with aryl sulfamates and tosylates
Agrawal, Toolika,Cook, Silas P.
supporting information, p. 96 - 99 (2013/03/28)
The iron-catalyzed cross-coupling of aryl sulfamates and tosylates has been achieved with primary and secondary alkyl Grignards. This study of iron-catalyzed cross-coupling reactions also examines the isomerization and β-hydride elimination problems that are associated with the use of isopropyl nucleophiles. While a variety of iron sources were competent in the reaction, the use of FeF3·3H2O was critical to minimize nucleophile isomerization.
Cross-coupling reactions through the intramolecular activation of Alkyl(triorgano)silanes
Nakao, Yoshiaki,Takeda, Masahide,Matsumoto, Takuya,Hiyama, Tamejiro
supporting information; scheme or table, p. 4447 - 4450 (2010/08/19)
(Figure Presented) Cross-Si-ing the Jordan: Cross-coupling reactions of 2-(2-hydroxyprop-2-yl)phenylsubstituted alkylsilanes with a variety of aryl halides proceed in the presence of palladium and copper catalysts. The use of K3PO4 base allows for highly chemoselective alkyl coupling with both primary and secondary alkyl groups (Alk).
A general and efficient suzuki-miyaura cross-coupling protocol using weak base and no water: The essential mole of acetate
Wang, Bing,Sun, Hui-Xia,Sun, Zhi-Hua
experimental part, p. 3688 - 3692 (2009/12/03)
A weak base, CsOAc, promotes Suzuki-Miyaura cross-coupling and related Pd-catalyzed reactions under anhydrous conditions as effectively as stronger bases. Aryl triflates exhibit unusual reaction rates, which are comparable to that: of bromoarenes. A negle
B-Alkyl Suzuki-Miyaura cross-coupling of tri-n-alkylboranes with arylbromides bearing acidic functions under mild non-aqueous conditions
Sun, Hui-Xia,Sun, Zhi-Hua,Wang, Bing
experimental part, p. 1596 - 1599 (2009/06/18)
An efficient and chemoselective Pd-catalyzed B-alkyl Suzuki-Miyaura cross-coupling of tri-n-alkylboranes with arylbromides possessing acidic functions is described. This protocol features the relatively weak base Cs2CO3 and mild non-
Direct B-alkyl Suzuki-Miyaura cross-coupling of trialkyl-boranes with aryl bromides in the presence of unmasked acidic or basic functions and base-labile protections under mild non-aqueous conditions
Wang, Bing,Sun, Hui-Xia,Sun, Zhi-Hua,Lin, Guo-Qiang
experimental part, p. 415 - 422 (2009/10/23)
An efficient and chemoselective palladium-catalyzed direct B-alkyl Suzuki-Miyaura cross-coupling of trialkylboranes with diversely functionalized aryl bromides is described. A wide variety of unmasked acidic or basic functions are tolerated. The mild non-
Synthesis and antiviral evaluation of 6-(alkyl-heteroaryl)furo[2,3-d] pyrimidin-2(3H)-one nucleosides and analogues with ethynyl, ethenyl, and ethyl spacers at C6 of the furopyrimidine core
Robins, Morris J.,Nowak, Ireneusz,Rajwanshi, Vivek K.,Miranda, Karl,Cannon, John F.,Peterson, Matt A.,Andrei, Graciela,Snoeck, Robert,De Clercq, Erik,Balzarini, Jan
, p. 3897 - 3905 (2008/02/10)
Sonogashira coupling strategies were employed to synthesize new furo[2,3-d]pyrimidin-2(3H)-one (FuPyrm) 2′-deoxynucleoside analogues. Partial or complete reduction of ethyne-linked compounds afforded ethenyl-and ethyl-linked derivatives. Levels of inhibition of varicella-zoster virus (VZV), human cytomegalovirus (HCMV), a broad range of other DNA and RNA viruses, and several cancer cell lines were evaluated in cell cultures. The anti-VZV potency decreased with increasing rigidity of the side chain at C6 of the FuPyrm ring in the order dec-1-yn-1-yl dec-1-en-1-yl decan-1-yl. In contrast, compounds with a rigid ethynyl spacer between C6 of the FuPyrm ring and a 4-alkylphenyl moiety were more potent inhibitors of VZV than the corresponding derivatives with an ethyl spacer. Replacement of the phenyl moiety in 6-(4-alkylphenyl) derivatives with a pyridine ring (in either regioisomeric orientation) gave analogues with increased solubility in methanol but reduced anti-VZV potency, and replacement with a pyrimidine ring reduced the anti-VZV activity even further. The pyridine-ring-containing analogues were ~20-fold more potent inhibitors of VZV than acyclovir but were ~6-fold less potent than BVDU and ~60-fold weaker than the most active 6-(4-pentylphenyl)- substituted prototype.